Preheat the oven to 350°F and grease two 6-inch round cake pans.
In a mixing bowl, beat the first ½ cup butter with the sugar until light. Add the eggs one at a time, then mix in the milk and vanilla extract.
Stir in the flour until the batter is smooth. Divide the batter evenly into three bowls.
Leave one bowl plain, tint the second bowl yellow, and tint the third bowl orange.
Spoon the three colors into each pan in alternating layers, then gently swirl once with a knife.
Bake for 22-25 minutes until a toothpick comes out clean. Cool the layers completely on a wire rack.
Beat the remaining ½ cup butter with the powdered sugar until creamy to make the frosting.
Spread frosting over the cooled layers, stack them, and finish with more frosting on top. Arrange candy corn pieces across the surface.