Preheat your oven to 350°F (175°C) and prepare two 9-inch round cake pans by greasing them with butter and dusting with flour or lining with parchment paper.

In a large mixing bowl, sift together the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking powder, baking soda, and salt.

In another bowl, beat together the eggs, whole milk, vegetable oil, and vanilla extract until smooth and creamy.

Gradually pour the wet ingredients into the bowl with your dry ingredients, mixing gently until just combined.

Carefully stir in the boiling water to the batter until combined.

Divide the mixture evenly between the prepared cake pans and bake for 30-35 minutes.

Once baked, remove the cakes from the oven and let them cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

Prepare the frosting by beating the softened unsalted butter with sifted cocoa powder until smooth. Gradually mix in the powdered sugar and milk until fluffy.

Mix in the vanilla extract and a pinch of salt to the frosting. Once the cake layers are completely cooled, spread frosting between the layers and on top and sides of the cake.