Chunky Monkey Oatmeal Cookie Skillet

Featured in: Sweet Smile

This indulgent cast-iron skillet dessert combines the beloved Chunky Monkey trio—ripe bananas, semisweet chocolate chips, and toasted walnuts—into a warm, gooey oatmeal cookie base. Baked until golden with slightly crisp edges and a soft center, this shareable treat comes together in just 40 minutes using simple pantry ingredients. Perfect for serving straight from the pan with vanilla ice cream, it offers the nostalgic comfort of classic banana bread meets chocolate chip cookies in an impressive yet effortless presentation.

Updated on Sun, 08 Feb 2026 11:56:00 GMT
Warm Chunky Monkey Oatmeal Cookie Skillet topped with vanilla ice cream melting into gooey chocolate chips and walnuts. Save
Warm Chunky Monkey Oatmeal Cookie Skillet topped with vanilla ice cream melting into gooey chocolate chips and walnuts. | grinnosh.com

My roommate came home with a blender full of Chunky Monkey smoothie dreams one Saturday afternoon, and I watched her drink it while standing at the kitchen counter, thinking there had to be a way to bake those flavors into something you could actually sit down with. This skillet cookie was born from that exact moment—banana, chocolate, and walnuts all coming together in a warm, golden pan that hits the table still crackling slightly from the oven. It's the kind of dessert that feels special without demanding your undivided attention or a stand mixer.

I made this for my book club last month, and someone asked if I'd bought it from a bakery before I sheepishly admitted I'd baked it that afternoon. There's something about pulling a skillet straight from the oven to the center of the table that makes people think you've planned an elaborate dessert, when really you've just mixed wet and dry and let the oven do the heavy lifting. The whole room smelled like toasted chocolate and caramelized banana before we'd even finished dinner.

Ingredients

  • Old-fashioned rolled oats (1 ½ cups): These give the skillet cookie its chewy, textured heart—steel-cut oats will make it too dense, and quick oats disappear entirely, so stick with the classic rolled kind.
  • All-purpose flour (1 cup): This is your structure; don't skip it or substitute with oat flour without adjusting liquid, or you'll end up with something more pudding than cookie.
  • Baking soda and baking powder (½ teaspoon each): The baking soda reacts with the banana's natural acidity while the baking powder gives gentle lift—use fresh leavening agents or your skillet will stay stubbornly flat.
  • Unsalted butter, melted (½ cup): Melted butter distributes evenly through the batter and keeps the skillet cookie tender rather than cakey, and melting it yourself beats softened butter every time for this recipe.
  • Brown and granulated sugar (⅓ cup each): The brown sugar adds moisture and molasses depth while the granulated sugar keeps the edges crisp—using both is the secret to texture.
  • Large egg: One egg is enough to bind everything without making this taste eggy, which is the opposite of what you want in an oatmeal cookie.
  • Ripe bananas, mashed (2 medium, about 1 cup): They need to be spotty and soft enough that they practically mash themselves, or they won't incorporate smoothly into the batter.
  • Semisweet chocolate chips and chopped walnuts (½ cup each): The chips melt slightly into little pockets of flavor while the walnuts toast and turn nutty, creating little moments of texture throughout.
  • Dark chocolate, chopped (½ cup, optional): Add this only if you want the skillet cookie to feel more indulgent—it's not necessary but it absolutely transforms the flavor if you do.

Instructions

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Heat your oven and prep the pan:
Set the oven to 350°F and butter a 10-inch cast-iron skillet or any oven-safe pan you have on hand. Cast iron retains heat beautifully and gives you those slightly caramelized edges, but any oven-safe vessel works fine here.
Combine the dry team:
In a medium bowl, whisk together the oats, flour, baking soda, baking powder, and salt until everything is evenly distributed and the baking soda's pale yellow specks disappear into the mix. Set this aside and resist the urge to touch it again.
Marry the wet ingredients:
In a large bowl, stir the melted butter with both sugars until the mixture looks sandy and combined, then crack in the egg and add the vanilla and beat it until it's pale and creamy. This usually takes about a minute of vigorous stirring, and you'll feel it shift under your spoon.
Fold in the bananas:
Stir the mashed bananas into the wet mixture until there are no white streaks left and the batter takes on a golden color. Don't worry if a few small banana chunks remain—those are flavor bombs waiting to happen.
Bring wet and dry together:
Pour the dry ingredients into the wet mixture and fold gently with a rubber spatula until just barely combined. Stop as soon as you don't see any flour streaks, because overmixing creates a tough, dense skillet cookie and we're after tender and yielding here.
Add the mix-ins with care:
Gently fold in the chocolate chips and walnuts, then the dark chocolate if you're using it, being careful not to break down the bananas further or overwork the batter. Let the mix-ins distribute themselves naturally—this isn't the moment to be thorough.
Transfer to the skillet:
Scrape the batter into your prepared skillet and spread it in an even layer using the back of the spatula, smoothing the top gently. Don't press down hard or you'll create a dense bottom layer.
Bake until golden:
Slide the skillet into the oven and bake for 22 to 25 minutes, until the edges are golden brown and smell irresistible. A toothpick inserted in the center should come out with a few moist crumbs clinging to it—not completely clean, because a few moist crumbs mean moist cookie and that's the goal.
Cool and serve:
Let the skillet rest on the counter for about 10 minutes—this allows it to set just enough to slice cleanly but it'll still be warm and soft when you dig in. Serve straight from the skillet with vanilla ice cream if you're feeling indulgent.
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Freshly baked Chunky Monkey Oatmeal Cookie Skillet with golden edges and a soft center in a cast-iron pan. Save
Freshly baked Chunky Monkey Oatmeal Cookie Skillet with golden edges and a soft center in a cast-iron pan. | grinnosh.com

Last week, my neighbor knocked on my door right as I was pulling this from the oven, and the smell hit them before they even said hello. By the time I'd plated a warm slice with ice cream melting into it, we were sitting on my porch talking until the sun went down, and that's when I realized this skillet cookie had become less about the recipe and more about the excuse to slow down and share something warm with someone.

Why Cast Iron Matters Here

Cast iron conducts heat differently than aluminum or steel—it holds warmth longer and distributes it more evenly across the bottom, which is why the edges get those perfect caramelized corners while the center stays tender. If you don't have cast iron, use whatever oven-safe pan you have, but expect the baking time might shift by a couple of minutes depending on how thick the pan is. The cast iron also means you can bring the whole skillet straight to the table, and there's an elegance in that gesture that matters when you're sharing food with people you care about.

Making It Your Own

This recipe is flexible in the way the best desserts are—the banana is your anchor, the chocolate and walnuts are negotiable. I've subbed pecans for walnuts when that's what I had on hand, stirred in dried cherries alongside the chocolate, even scattered a handful of shredded coconut on top before baking. The formula stays the same because the wet and dry ratio is balanced, so you can swap mix-ins without second-guessing yourself.

Serving Suggestions and Storage

This skillet cookie is best eaten the day it's made, while the texture is still at its softest and the banana flavor hasn't started to fade. If you've somehow got leftovers, cover the skillet loosely with foil and leave it on the counter—reheating it gently in a 300°F oven for about 5 minutes brings back that just-baked warmth, and a scoop of ice cream masks any slight staleness that might have crept in. For storage beyond a day, wrap individual slices and refrigerate for up to three days, though let them come to room temperature or warm them slightly before eating, because cold skillet cookie loses its charm.

  • Serve it warm, ideally within an hour of baking, when the chocolate is still slightly soft and the walnuts are still toasty.
  • Vanilla ice cream is the obvious pairing, but brown butter ice cream or salted caramel are both unexpectedly wonderful here.
  • Leftover pieces make excellent next-morning breakfast when crumbled over yogurt, though nobody would fault you for eating them straight from the fridge at midnight.
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Ripe bananas and dark chocolate chunks baked into a shareable Chunky Monkey Oatmeal Cookie Skillet served warm. Save
Ripe bananas and dark chocolate chunks baked into a shareable Chunky Monkey Oatmeal Cookie Skillet served warm. | grinnosh.com

This skillet cookie sits somewhere between homemade and effortless, which is exactly where comfort food lives. Make it for yourself on a quiet evening, or pull it from the oven when someone unexpected stops by and watch their face light up at the smell alone.

Recipe FAQ

Can I make this skillet dessert ahead of time?

Yes, you can prepare the batter up to 24 hours in advance and store it covered in the refrigerator. Let it come to room temperature for about 20 minutes before baking, or add 2-3 extra minutes to the baking time if baking cold.

What can I use instead of a cast-iron skillet?

Any 10-inch oven-safe pan works well, including ceramic baking dishes, cake pans, or even pie dishes. Adjust baking time as needed—shallower pans may bake slightly faster, while deeper dishes may need a few extra minutes.

How do I know when it's finished baking?

The edges should appear golden brown and slightly set, while the center may still look slightly soft. A toothpick inserted in the middle should come out with moist crumbs rather than wet batter. The center will continue to set as it cools.

Can I freeze leftovers?

Absolutely. Cut into portions, wrap individually in plastic wrap and foil, then freeze for up to 3 months. Reheat in the microwave for 30-45 seconds or in a 350°F oven for 8-10 minutes until warmed through.

What other mix-ins work well in this skillet?

Try swapping walnuts for pecans, adding dried cherries or cranberries, mixing in peanut butter chips, or sprinkling coconut on top. Cinnamon or nutmeg in the batter adds warm spice notes that complement the banana beautifully.

Is this suitable for vegans?

Yes, with simple substitutions. Replace butter with melted coconut oil, use a flax egg (1 tablespoon ground flaxseed mixed with 2.5 tablespoons water), and ensure your chocolate chips are dairy-free. The results remain equally delicious.

Chunky Monkey Oatmeal Cookie Skillet

Warm banana chocolate walnut oatmeal skillet baked to golden perfection. An easy, shareable dessert inspired by classic Chunky Monkey flavors.

Prep duration
15 min
Cook duration
25 min
Complete duration
40 min
Created by Hannah Lewis


Skill level Easy

Heritage American

Output 8 Portions

Dietary guidelines Meat-free

Components

Dry Ingredients

01 1½ cups old-fashioned rolled oats
02 1 cup all-purpose flour
03 ½ teaspoon baking soda
04 ½ teaspoon baking powder
05 ¼ teaspoon salt

Wet Ingredients

01 ½ cup unsalted butter, melted
02 ⅓ cup light brown sugar, packed
03 ⅓ cup granulated sugar
04 1 large egg
05 1 teaspoon pure vanilla extract

Chunky Monkey Add-ins

01 2 ripe bananas, mashed (approximately 1 cup)
02 ½ cup semisweet chocolate chips
03 ½ cup chopped walnuts
04 ½ cup chopped dark chocolate, optional

Directions

Stage 01

Prepare the skillet: Preheat oven to 350°F. Grease a 10-inch cast-iron skillet with butter or nonstick spray.

Stage 02

Combine dry ingredients: In a medium bowl, whisk together oats, flour, baking soda, baking powder, and salt. Set aside.

Stage 03

Mix wet base: In a large bowl, combine melted butter, brown sugar, and granulated sugar, mixing until creamy.

Stage 04

Incorporate egg and banana: Beat egg and vanilla extract into the butter mixture, then stir in mashed bananas until fully incorporated.

Stage 05

Combine wet and dry: Gradually fold dry ingredients into wet mixture until just combined, avoiding overmixing.

Stage 06

Add mix-ins: Gently fold in chocolate chips, walnuts, and chopped dark chocolate if using.

Stage 07

Transfer to skillet: Spread batter evenly into prepared skillet.

Stage 08

Bake: Bake for 22 to 25 minutes until edges are golden and a toothpick inserted in center comes out mostly clean with a few moist crumbs.

Stage 09

Cool and serve: Cool for 10 minutes before serving. Serve warm directly from skillet, optionally topped with vanilla ice cream.

Necessary tools

  • 10-inch cast-iron skillet or oven-safe baking pan
  • Mixing bowls
  • Whisk
  • Rubber spatula
  • Measuring cups and spoons

Allergy details

Review each component for potential allergens and consult with healthcare professionals if you're uncertain about ingredients.
  • Contains wheat and gluten
  • Contains eggs
  • Contains milk products including butter and chocolate chips
  • Contains tree nuts including walnuts

Nutrient content (per portion)

These values are approximate guidelines only and shouldn't replace professional nutritional advice.
  • Energy: 310
  • Fats: 15 g
  • Carbohydrates: 41 g
  • Proteins: 5 g