Preheat that oven to 350°F (175°C). Then, grease and flour three 9-inch round cake pans, or line them with parchment paper.
Thoroughly whisk the flour, baking powder, baking soda, and salt until well combined.
Beat that softened butter and sugar together until it's light with your electric mixer. You want that perfect texture for your cake, so give it about 3-4 minutes of mixing.
Add your eggs one at a time, beating well after each one. Then, stir in the vanilla extract.
Now, slowly add the buttermilk to the butter-sugar mixture, alternating with the dry ingredients you prepared earlier. Start with the dry ingredients and end with them, so you get a smooth, creamy batter.
Mix in the purple food coloring . Keep mixing until the batter turns a gorgeous, vibrant purple.
Now, divide the batter evenly between the three prepared cake pans and pop them in the oven. Bake for approximately 30 minutes. Let the cakes cool (Important).
Beat together your softened butter and cream cheese until it’s smooth and creamy. Gradually add the powdered sugar and keep beating until it’s fluffy. Add purple food coloring and a splash of vanilla extract.
Once the cakes are cool, place the first layer on your cake stand or plate. Spread a generous layer of that creamy frosting over it, then add the second layer. Frost it up again and repeat with the third layer. Enjoy!