Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans, or use a 9x13-inch baking dish. Line the bottom with parchment paper for easy removal.

In a large bowl, sift together flour, baking powder, baking soda, cocoa powder, sugar, and salt.

Add the eggs, milk, vegetable oil, and vanilla extract to the dry ingredients. Mix with a hand mixer or whisk until smooth. Don’t overmix—just combine until incorporated.

Stir in the boiling water. The batter will be thin, but that’s normal.

Mix in the sour cream to make the cake extra soft and moist.

Pour the batter evenly into the prepared pans. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

Once the cakes are cool, frost with your favorite frosting. Hershey’s chocolate frosting is a classic choice, but you can also use vanilla frosting, whipped cream, or powdered sugar.