Very Chocolate Layer Cake

• 1/4 cup softened butter
• 1/4 cup Crisco or other good shortening
• 2 cups sugar
• 1 teaspoon vanilla extract
• 2 eggs, at room temperature
• 1-3/4 cups all-purpose flour, unsifted
• 3/4 cup cocoa
• 1-1/2 teaspoons baking powder
• 1/2 teaspoon baking soda
• 1/2 teaspoon salt
• 1-3/4 cup milk