Preheat oven to 350º F. Prepare three 9-inch round cake pans with nonstick baking spray or coated well with shortening or butter and floured, taking care to remove all excess flour.
Cream together butter and shortening until light and fluffy with an electric mixer. Slowly add sugar one cup at a time, making sure to fully incorporate each cup before adding another. Add eggs one at a time, making sure to fully incorporate each egg before adding another.
Sift together flour, baking powder, and salt. Pour milks and vanilla into measuring cup and whisk together with a fork. Add to butter and shortening mixture alternately with milk mixture, beginning and ending with dry ingredients.
Gently stir all ingredients until well combined. Stop mixer and scrape down sides and bottom of bowl, making sure to have all ingredients mixed well.
Evenly distribute cake batter between cake pans and place pans into oven. Bake for 25-30 minutes, or until a toothpick or cake tester inserted in the center comes out clean. Remove and allow to cool slightly in cake pans for about 5 minutes, then cool completely on a wire rack.
Frost cake as desired.
Some people have had problems with the cake not rising. Try creaming the butter shortening, and sugar until light and fluffy, about 3 to 5 minutes. Don't over beat when adding eggs and other ingredients, just mix gently until incorporated well into batter. -This recipe makes approximately 24 cupcakes when cupcake tin is filled more than 3/4 full. When filled 1/2 full, this recipe makes approximately 36 cupcakes. Bake approximately 18 minutes. - If you preferred the original white cake recipe, it used 1/2 teaspoon baking powder and 1 cup buttermilk with no whole milk. - If you live in a high altitude environment, you'll need to make sure to follow recommended baking adjustments for your altitude.