Preheat the oven to 350°F (180°C). Butter the bottom of three 7-inch round pans and line with baking paper.

In the bowl of an electric mixer, mix together the cake flour, sugar, baking powder, baking soda, and salt on low speed with the paddle attachment for 1 minute.

Keeping the mixer on low speed, add the cubed butter and combine until the mixture resembles coarse sand (about 4 minutes).

In a separate bowl, whisk together the oil, eggs, buttermilk, and vanilla. With the mixer on low speed, gradually add the wet ingredients and mix just until combined.

Weigh out equal amounts into 3 7-inch cake pans. Tint the cakes with food coloring (I used Wilton’s blue, pink and violet). Bake for about 35 minutes or until a toothpick inserted into the center comes out clean. Let the cakes cool completely before decorating.

To make Swiss Meringue buttercream:

In a large saucepan, place mixing bowl over a pot of barely simmering water. Add egg whites and cups sugar and whisk together until frothy. Whisk constantly until mixture reaches 160˚F (takes about 3 min). Sugar should be fully dissolved (no granules when rubbing mixture between finger tips). Mixture will feel hot to the touch (or like the temperature of warm milk).

Once bowl is at room temperature, switch to paddle attachment, and whip together until soft peaks form. Add butter 1 Tbsp at a time. Once all butter is in, scrape down the bowl and continue beating until it reaches a thick whipped consistency. It may look lumpy – it’s a good sign, keep beating until it changes consistency to become smooth, thick and whipped. Add vanilla extract and salt and mix on med-high until incorporated and silky.

To Assemble and Decorate:

Trim off excess of the layers (freeze before hand helps). Place first first layer on cake board, making sure to frost between each layer and crumb coat. Use a cake turntable to smooth white frosting over entire cake.

Use white fondant to make a unicorn horn ears. Create edible gold dust and then brush it onto the horn. Pipe rosettes on the top and along side of the cake using the pink, blue and light purple frostings. Pipe eyes onto the front center of cake.