– 3 ½ cups All-purpose flour – 2 teaspoon Baking powder – ¾ teaspoon Baking soda – 1 teaspoon Salt – ¾ cup Unsalted butter room temperature – ¼ cup Oil canola or vegetable oil – 1 ½ cups White granulated sugar – ¼ cup Sour cream room temperature – 1 tablespoon Clear imitation vanilla you can use pure vanilla extract – 4 Large eggs room temperature – 1 cup Buttermilk room temperature – Food dye coloring red, orange, yellow, green, blue – 2 cups Unsalted butter slightly cold – 10 oz Cream cheese room temperature – 8 ½ cups Powdered sugar sifted – ½ teaspoon Salt – 1 teaspoon Pure vanilla extract – ⅓ cup Heavy cream – Food dye coloring to make rainbow frosting
Preheat oven to 350°F. Spray three 8-inch cake pans with nonstick. For cake pan bottoms, use 8-inch paper circles. Spray again.Sift flour in a medium bowl. Add baking powder, soda, and salt. Set aside.
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Mix butter, oil, and sugar on high for 3 minutes. Very fluffy. Scrape bowl. Add vanilla and sour cream and mix on medium.Add eggs one at a time and beat on high for 2 minutes. Scrape bowl.
2
Add ⅓rd dry ingredients and half buttermilk. Mix low. Stir in another ⅓rd of dry ingredients and remaining buttermilk. Finish using dry ingredients.Fill three cake pans with batter. Apply 2 drops of each food color evenly on the cake.
3
Blend colors using a butter knife.Bake the cake 18–23 minutes. Bake until toothpick comes out clean. Put the cakes on a cooling rack after 10 minutes in heated pans. Let cakes cool fully.
4
Wait 30 minutes to slowly cool the butter on the counter. Sift powdered sugar while waiting.Mix butter and cream cheese on high for 2 minutes. Scrape the bowl and add powdered sugar gently. Quite thick.
5
Combine vanilla, salt, and heavy cream. Beat on low until merged, then speed up. Beat 1-2 minutes to foam.Save 1 ½ cups of frosting. Add rainbow colors to 4-5 bowls.
6
Cover with plastic. Spread each color vertically on plastic. Cut one end of the plastic wrap. Set aside.Frost your ornamental board. Level domed cakes using a serrated knife.
7
Place the first cake layer. Evenly apply 1 cup frosting. Repeat layers two and three.Coat the cake lightly with icing. Freeze for 15 minutes to set crumbs.
8
Finish frosting the cake.Piping bag with Wilton 1M tip must be big. Top the cake with big swirls or borders.
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