Preheat oven to 350°F and prepare two 9-inch cake pans.

Whisk together flour, baking powder, and salt.

Cream butter and sugar until light and fluffy.

Beat in eggs one at a time.

Alternate adding the dry ingredients and milk, mixing just until combined.

Stir in vanilla extract.

Divide batter evenly between pans.

Bake for 28–32 minutes, until a toothpick inserted into the center comes out clean.

Cool in pans for 10 minutes, then transfer to a wire rack to cool completely.

Beat butter for the frosting until creamy.

Gradually add powdered sugar and cocoa powder.

Slowly mix in milk, vanilla, and salt until smooth and fluffy.

Frost between the cake layers and over the top and sides.

Let the cake rest for at least 30 minutes before slicing for the cleanest cuts.