This decadent cake mirrors the Valley of Ashes, a place of desolation between West Egg and New York City, representing the moral decay hidden beneath the surface of the characters' lives.
Preheat oven to 350°F (175°C).
In a large bowl, combine flour, sugar, cocoa powder, baking powder, and salt.
Add melted butter, eggs, and vanilla extract. Mix until smooth.
Pour batter into a greased 9-inch round cake pan.
Bake for 25 minutes or until a toothpick inserted in the center comes out clean.