Rocky Road Brownie Layer Cake with Chocolate Ganache

Heat the oven to 350°F (175°C). Grease and flour three 9-inch (23 cm) round cake pans and line the bottoms with parchment.

Melt the butter and let it cool slightly. Whisk in the sugar, then the eggs one at a time, then the vanilla, until glossy.

Sift the flour, cocoa, salt and baking powder over the bowl and fold just until no dry streaks remain. Fold in 1 cup of pecans.

Divide the batter evenly among the three pans. Bake for 20 to 25 minutes, until a toothpick in the center comes out with a few moist crumbs but no wet batter. Cool in the pans for 15 minutes, then turn out and cool completely.

For the ganache, heat the cream until it just begins to simmer, then pour it over the chocolate chips and dark chocolate in a bowl. Let stand for 5 minutes, then stir until smooth. Cool for about 30 minutes, until thick but still pourable.

Place one brownie layer on a serving plate. Microwave 1/2 cup of mini marshmallows in a small bowl for 15 to 20 seconds until puffed, and quickly spread them over the layer.

Add the second brownie layer, spread it with the rest of the melted marshmallows, then top with the third layer.

Pour the ganache over the top and spread it down the sides.

Scatter the remaining pecans and mini marshmallows over the top and let the ganache set for about 1 hour before slicing.