1. Preheat oven to 350°F/180°C. Butter three 9-inch cake pans, and line the bottoms with parchment paper.

Make the cake

1. In a medium bowl, sift together flour, baking powder, and salt. Set aside.

2. In the bowl of an electric mixer fitted with the paddle attachment, beat butter, oil, and sugar on medium speed until light and fluffy, 3-4 minutes. Scrape down the sides and bottom of the bowl as needed.

3. Add eggs, one at a time, beating well after each addition. Beat in vanilla extract.

4. With the mixer on low speed, add the flour mixture in three additions alternating with the milk in two additions, beginning and ending with the flour mixture. Do not overmix the batter. The less you mix, the lighter the cake will be.

Dye the batter and bake

1. Divide the batter as evenly as possible into three bowls. Add food coloring to each bowl until desired color is reached. Add just a tiny drop at first because food colorings can be very concentrated.

2. Pour each bowl of batter into prepared pans. Bake for 25-30 minutes until a toothpick inserted into the center of the cakes comes out clean.

   Allow cakes to cool for 15 minutes, then gently remove from pans and allow them to cool completely on a wire rack.

Make the frosting

1. In the bowl of an electric mixer fitted with the paddle or whisk attachment, beat butter and salt on medium speed until smooth and creamy, about 2 minutes.

2. Add 5 cups powdered sugar, heavy cream, and vanilla. Beat on low speed for 30 seconds, then increase speed to high and beat for 2 minutes. Beat in more powdered sugar if frosting is too thin.

Assemble the cake

1. If the cakes rose too much, cut their rounded top with a knife to make them flat. Set one cake layer on a plate or cake stand.

   Once cakes are completely cooled, evenly spread a thick layer of the frosting over the cake to the edge.

2. Top with the second cake layer and spread a thick layer of the frosting. Finish with the third cake layer. Spread frosting over the top and sides of the cake.