Gooey Marshmallow Brownie Skillet

f you're the type of person who always reaches for the corner brownie because it's extra fudgy, or you can't resist anything inspired by s'mores, this Gooey Marshmallow Brownie Skillet is about to become your new favorite dessert.

This skillet brownie starts with a rich brown butter brownie batter that's packed with melted chocolate and chopped chocolate chunks. Hidden throughout are little pockets of gooey marshmallow fluff that melt into the brownies as they bake. Then, because more marshmallow is always a good idea, it's finished with toasted marshmallow fluff, extra chocolate, and a sprinkle of flaky sea salt.

The result is somewhere between a fudgy brownie, a skillet cookie, and a classic campfire s'more.

Serve it warm with a scoop of vanilla ice cream and plenty of spoons because this is definitely a dessert worth sharing.

Why is this Brownie Skillet so Good? 

This isn't just a brownie baked in a skillet.

A few simple techniques make it extra special:

• Brown butter adds rich, caramel-like flavor.
• A little vegetable oil keeps the brownies extra fudgy.
• Marshmallow fluff is added in dollops instead of one solid layer, creating gooey pockets throughout the brownies.
• A toasted marshmallow topping gives it that classic s'mores flavor without needing a campfire.

Every bite has a little something different, which makes this dessert so fun to eat.

Gooey Marshamallow Brownie Skillet Ingredients

Unsalted Butter: Browning the butter adds incredible depth and gives these brownies a rich, nutty flavor.

Vegetable Oil: A small amount of oil helps keep the brownies soft and fudgy, even after they've cooled.

Semi-Sweet Chocolate Chips: Melted into the batter for a rich chocolate base.

Granulated Sugar: Adds sweetness while helping create that shiny brownie top.

Light Brown Sugar: Adds moisture and a subtle caramel flavor.

Eggs + Egg Yolk: The extra egg yolk is the secret to a rich, fudgy texture.

Vanilla Extract: Rounds out all of the chocolate flavors.

All-Purpose Flour: Just enough flour to give the brownies structure without making them cakey.

Dutch-Process Cocoa Powder: Deepens the chocolate flavor and creates a darker, richer brownie.

Salt: Balances the sweetness and enhances the chocolate.

Chopped Chocolate: Creates melty pockets of chocolate throughout the brownies.

How to Brown Your Butter

Brown butter is one of my favorite ways to make chocolate desserts taste even richer.

Simply melt the butter over medium heat, stirring occasionally. After a few minutes, it will begin to foam before turning golden brown with little brown bits at the bottom of the pan.

Once it smells warm and nutty, remove it from the heat immediately to prevent burning.

Those little browned milk solids are packed with flavor, so don't leave them behind.

How to Make Gooey Marshmallow Brownie Skillet

Step 1: Prep the Skillet - Preheat your oven to 350°F.

Lightly grease an 8-inch cast iron skillet.

Step 2: Brown the Butter - Brown the butter over medium heat until golden brown and fragrant. Whisk in the vegetable oil and allow the mixture to cool for about 10 minutes.

Step 3: Melt the Chocolate - Whisk the chocolate chips into the warm butter until smooth.

Step 4: Add the Wet Ingredients - Whisk in both sugars. Add the eggs, egg yolk, and vanilla extract. Continue whisking until smooth and glossy.

Step 5: Add the Dry Ingredients

Fold in:

• flour
• cocoa powder
• salt

Mix just until combined. Fold in the chopped chocolate.

Step 6: Assemble - Spread half of the brownie batter into the prepared skillet.

Dollop teaspoon-sized mounds of marshmallow fluff all over the batter.

Rather than spreading the fluff into one layer, leave it in little dollops. This creates gooey marshmallow pockets throughout the brownies.

Top with the remaining brownie batter.

It's completely fine if a little marshmallow peeks through.

Step 7: Bake - Bake for 24–30 minutes. The edges should be set while the center still has a slight jiggle. The brownies will continue setting as they cool.

Step 8: Toast the Marshmallow - As soon as the skillet comes out of the oven, dollop extra marshmallow fluff over the top.

Place the skillet under the broiler for 30–60 seconds, or use a kitchen torch until the marshmallow is lightly toasted.

Watch it carefully because marshmallow browns quickly.

Step 9: Finish and Serve

Top with:

• chopped chocolate
• graham cracker crumbs (optional)
• flaky sea salt

Serve warm with vanilla ice cream.

Trust me on this part.

Tips for the Best Brownie Skillet

Brown the Butter: Don't skip this step. Brown butter adds so much flavor.

Dollop the Marshmallow: Little pockets are much better than one thick layer because every bite gets gooey marshmallow.

Don't Overbake: The center should still have a slight jiggle when you remove it from the oven.

Serve Warm: This dessert is at its absolute best while the chocolate is melty and the marshmallow is still gooey.

Fun Variations

Peanut Butter Brownie Skillet

Swirl peanut butter into the brownie batter before baking.

Cookies and Cream Version

Add chopped Oreos to the brownie batter.

Triple Chocolate

Use milk, dark, and semi-sweet chocolate together.

S'mores Brownie Skillet

Add crushed graham crackers between the brownie batter and marshmallow layer.

Storage

Refrigerator

Cover the skillet or transfer leftovers to an airtight container and refrigerate for up to 4 days.

Reheating

Warm individual servings in the microwave for 20–30 seconds to make the chocolate and marshmallow gooey again.

Frequently Asked Questions

1. Can I use mini marshmallows instead of marshmallow fluff? Yes, but marshmallow fluff creates softer, gooier pockets throughout the brownies.
2. Why add vegetable oil? The small amount of oil helps keep the brownies extra fudgy and moist.
3. Can I bake this in a square pan? Absolutely. An 8x8-inch baking pan works well, though you won't get the same crisp skillet edges.
4. Can I skip browning the butter? You can, but browning the butter gives these brownies their signature rich flavor.