Simple Gooey S’mores Brownie Recipe with Marshmallow Fluff
These rich, gooey s’mores brownies start with a buttery graham cracker crust, melt-in-your-mouth Hershey’s chocolate bar layer, and ultra-fudgy homemade brownie batter—all crowned with a layer of toasted marshmallow fluff. They're the perfect nostalgic treat for summer nights or anytime you want campfire flavor from your oven.
Ingredients
For the Graham Cracker Crust:
- 1 1/2 cups graham cracker crumbs (about 10 full crackers)
- 6 tbsp unsalted butter, melted
- 2 tbsp granulated sugar
- 1/4 tsp salt
For the Hershey's Chocolate Layer:
For the Gooey Brownie Batter:
- 3/4 cup unsalted butter (1 ½ sticks)
- 6 oz semisweet chocolate (chopped or chips)
- 1 cup granulated sugar
- 1/2 cup light brown sugar
- 3 large eggs
- 1 tsp vanilla extract
- 3/4 cup all-purpose flour
- 1/4 cup unsweetened cocoa powder
- 1/2 tsp salt
For the Marshmallow Fluff Topping:
Instructions
Prepare the Crust
- Preheat oven to 350°F (175°C). Line an 8x8 or 9x9 inch square baking pan with parchment paper, leaving overhang on the sides.
- In a bowl, mix graham cracker crumbs, melted butter, sugar, and salt until evenly moistened.
- Press mixture firmly into the bottom of the prepared pan. Use the bottom of a glass to pack it down tightly and evenly.
- Bake the crust for 8 minutes, then remove from oven.
Add the Chocolate Layer
- While the crust is hot, lay full-sized Hershey’s bars across the crust in a single layer. Slightly overlap if needed to cover the majority of the surface.
Make the Gooey Brownie Batter (*see notes if using boxed mix)
- In a microwave-safe bowl, melt butter and chopped chocolate in 30-second intervals, stirring between each, until smooth.
- Whisk in granulated sugar and brown sugar while the mixture is still warm (this helps create that crackly top!).
- Add eggs and vanilla, whisking until fully combined and glossy.
- Sift in flour, cocoa powder, and salt. Gently fold with a spatula just until no dry streaks remain. Do not overmix—this keeps them fudgy.
Assemble & Bake
- Pour the brownie batter over the chocolate layer and smooth into an even layer.
- Bake at 350°F for 32–36 minutes, or until the edges are set and a toothpick inserted 2 inches from the edge comes out with a few moist crumbs. The center should still jiggle slightly.
- Cool completely in the pan on a wire rack for at least 1 hour before topping.
Top with Marshmallow Fluff & Toast
- Spread marshmallow fluff over the cooled brownies in an even layer. Place under the broiler for 30–60 seconds to toast. Watch closely—it can burn fast!
- Let cool briefly, then lift out using parchment overhang and slice into squares.
Video
Notes
*Shortcut tip: You can absolutely use a boxed brownie mix instead of making it from scratch—just follow the box directions and pour it over the Hershey’s layer after the crust. Reduce the bake time by 3–5 minutes since boxed mixes tend to bake faster. Choose a fudgy variety for best results.
Tips for Gooey Brownies
- Don’t overbake! Slightly underbaking is key for fudgy texture.
- Use a mix of melted butter + chopped chocolate + cocoa powder for deep flavor and richness.
- Let brownies cool fully before slicing to keep them clean and gooey in the center.