Two-Toned Cake

Preheat the oven to 350°F (180°C)

Forge a baking dish with parchment paper and grease it with butter. Reserve

Prepare the cake: In a stand mixer, beat the egg whites until stiff and reserve

In another bowl, cream together the butter and sugar until light and fluffy

In a large bowl, whisk together the flour, baking powder, and salt

With the mixer on low speed, gradually add the dry ingredients to the butter mixture, alternating with the milk, until smooth

Remove from the stand mixer and fold in the cocoa powder and egg whites, mixing delicately with a spatula

Pour into the prepared baking dish and bake at 350°F (180°C) for about 45 minutes

Remove from the oven, demold on a wire rack, and let cool

For the marshmallow topping: In a medium saucepan, combine the flour, salt, and hot water, whisking until smooth

Bring to a simmer over medium heat and cook without stirring until the mixture reaches 240°F (115°C) on a candy thermometer

In a stand mixer, beat the egg whites until stiff

With the mixer on low speed, slowly pour in the hot sugar mixture, beating constantly, until stiff peaks form

Remove from the stand mixer and let cool

For the chocolate topping: In a heatproof bowl set over a pot of simmering water, melt the dark chocolate, stirring occasionally

Melt only enough to achieve a smooth consistency

In a separate bowl, whisk together the confectioners' sugar, salt, and hot water until dissolved

Add the melted chocolate to the sugar mixture and whisk until combined

With an electric mixer, beat the egg yolks with the remaining confectioners' sugar until creamy

Add the softened butter and vanilla extract, beating until smooth

Pour into a piping bag fitted with a large round tip

Assemble the cake: Top half of the cake with marshmallow topping and dust with cocoa powder

Top the other half with chocolate topping

Serve at room temperature

Calories per slice: 458.