Preheat your oven to 350°F (175°C).

Grease and flour three 8-inch round cake pans or line them with parchment paper.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream together the butter and sugar until light and fluffy (about 3-4 minutes).

Add the eggs one at a time, mixing well after each addition, and then stir in the vanilla extract.

Gradually add the dry ingredients to the wet mixture, alternating with the milk, beginning and ending with the dry ingredients. Mix until smooth.

Divide the batter into 4-5 bowls (depending on the number of colors you want).

Add a few drops of food coloring to each bowl and stir until the desired color is achieved.

Spoon each color of batter into the prepared pans, layering the colors one by one.

Use a spatula or knife to swirl the batter slightly for a marble effect, if desired.

Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes, then transfer to wire racks to cool completely.

In a large bowl, beat the softened butter until creamy.

Gradually add powdered sugar, 1 cup at a time, beating until smooth.

Add the vanilla extract and heavy cream, then beat until the frosting reaches a smooth and spreadable consistency.

Divide the frosting into 4-5 bowls and color each with a different shade of food coloring.

Once the cakes are completely cool, level them if necessary.

Place the first layer on your cake stand or plate. Spread a layer of frosting over the top.

Add the second layer and repeat with frosting. Top with the third layer and cover the entire cake with a thin crumb coat of frosting to seal in any crumbs.

Refrigerate for 20 minutes to set the crumb coat.

Once the crumb coat is set, apply a thicker layer of frosting, smoothing it with a spatula.

Use different colored frosting to pipe rosettes, swirls, or other decorative elements around the cake.

Decorate with a unicorn horn and ears (either store-bought or made from fondant).

Optionally, add edible glitter or sprinkles for a magical touch.

Once decorated, the cake is ready to be served!

Slice, enjoy the fun, and watch as your guests marvel at the stunning unicorn cake.