A rich brownie base and crackly, chocolate, peanut butter rice-crunch topping sandwich a layer of perfectly fluffy and creamy marshmallow — three perfect textures in every bite.
Preheat the oven to 350°F. Line a 9×13-inch pan with non-stick foil (or parchment paper).
Make the brownies:
In a small bowl, whisk together the flour, cocoa powder and salt - set aside.
3/4 cup flour, 1/4 cup cocoa powder, 1 tsp salt
Place the butter and half the chocolate chips in a microwave safe bowl heat in 30 second bursts stirring in between until the butter and chocolate are fully melted and smooth. (You can also do this in a heat safe bowl over a saucepan of simmering water)
2 sticks butter, 6 oz chocolate chips
In a large bowl, beat the eggs, both sugars, vanilla and espresso powder on low speed; mix until it is thick and syrupy and all the sugar has dissolved.
4 eggs, 1 1/2 cups sugar, 1/2 cup brown sugar, 2 tsp vanilla, 1/2 tsp espresso powder
Whisk the chocolate mixture into the egg mixture until it is uniform in color, thick, smooth and glossy.
Stir in the flour mixture just until combined and no pockets of dry ingredients remain. Fold in the remaining chocolate chips.
6 oz chocolate chips
Pour into the prepared pan and bake for 25 to 28 minutes. The top should be dry and glossy, the edges should be set and slightly puffed, there may be some cracks in the surface. Remove from the oven and set aside to cool.
Add the filling:
Spread the marshmallow cream over the surface of the cooled brownies to within about 1/2 inch - 1/4 inch of the edge.
7 oz marshmallow creme
Make the topping:
In a large bowl, melt the peanut butter and chocolate chips together, either using 30 second bursts in the microwave or on the stovetop over a saucepan of simmering water.
1 cup creamy peanut butter, 1 1/2 cup semisweet chocolate chips
Quickly stir in the Rice Krispies cereal and immediately spoon the mixture over the marshmallow creme layer. Use a spatula to gently spread the Rice Krispies mixture until it is an even layer that completely covers the marshmallow.
3 cups Rice Krispies
Refrigerate until fully set before slicing into bars. Store in an airtight container at room temperature.
Notes
Variations:
If you don't want to use store bought marshmallow cream and you don't want to make your own marshmallow cream, you can substitute mini marshmallows instead.
When the brownies are about 5 minutes away from being done baking, remove them from the oven and distribute 8-10oz of mini marshmallows evenly over the surface.
Return the brownies to the oven to finish baking - the marshmallows should puff up a bit and form a melty, soft layer.
Follow the remainder of the recipe instructions for topping, cooling and cutting the brownies.
If you want to really take these brownies over the top, you can scatter a layer of mini/chopped peanut butter cups and peanut butter chips on top of the baked brownies and underneath the marshmallow layer.