Green Velvet Cake with Rainbow Frosting

Preheat the oven to 350ºF and prepare three 6-inch or two 8-inch cake pans by spraying the sides with cooking spray and placing a wax or parchment paper circle into the bottom of each one. Measure the sifted cake flour by spooning into your measuring cup and leveling it, or simply sift the cake flour into a bowl on your kitchen scale to measure it. Place the cake flour into a medium sized bowl and add the cocoa powder, baking soda, and salt. Whisk together and set aside.

Cream the butter on high for two minutes, then add the vegetable oil and sugar. Cream together on medium-high until light and fluffy, about 2 minutes. Scrape down the bowl and paddle. Turn the mixer to low and add the eggs one at a time. Once the eggs are incorporated, add the vanilla and white vinegar and mix on low for another 30 seconds. Scrape down the bowl and paddle once more.

Mix the green food color gel into the buttermilk. With the mixer on low speed, alternate adding the flour mixture and buttermilk in three additions, beginning and ending with the flour mixture. Mix only until the ingredients start to come together, then whisk the batter by hand a few times to make sure there are no large lumps.

Pour the batter into prepared cake pans (no more than 2/3 full) and bake for 30-35 minutes, until a toothpick inserted comes out clean. Let the cakes cool in the pan for five minutes before carefully removing them and placing the cakes on a wire rack or cookie sheet. Allow the cakes to cool completely before assembling and frosting.

With a hand mixer or paddle attachment on your stand mixer, cream the butter on medium-high until it’s creamy and light (almost white) in color. About 7 minutes.

With the mixer on low, add the sifted powdered sugar one cup at a time, scraping down after each addition and making sure each cup is fully incorporated before adding the next one.

Add vanilla, milk, and salt and mix on low for another minute until fully incorporated. Reserve the food coloring for step 2 of the assembly process.

Once the Green Velvet Cakes are cooled throughout, level and torte the layers to your desired height. Fill and stack the cake with vanilla buttercream topped with rainbow sprinkles. Crumb coat the cake and place it into the refrigerator for at least 30 minutes to let the crumb coat firm up.

To create the look pictured, reserve about 1 1/2 Cups of vanilla buttercream for the shell borders, then divide the rest of the buttercream evenly between 6 different bowls. Tint each bowl a different color of the rainbow: pink, orange, yellow, green, blue, and purple. Add each color into a piping bag and snip off 1/2 inch opening.

Mark out 6 equally sized sections on the side of the chilled crumb coated cake, then pipe the rainbow colors in order onto the side of the cake, one color per section. Use an icing smoother to create a smooth buttercream finish.

Add the uncolored buttercream into a piping bag fitted with Wilton Tip 4B, then pipe shell borders on the top and bottom of the cake before sprinkling with rainbow sprinkles.