Preheat your oven to 340°F.
Line three 6-inch round cake pans with parchment paper.
Mix the milk and vinegar together and set aside to thicken.
Stir in the remaining wet ingredients.
Sift the dry ingredients into the wet mixture.
Pour the batter evenly into the prepared pans.
Bake for 20-30 minutes, or until a toothpick comes out clean.
Let the cakes cool completely before leveling the tops.
In a mixing bowl, beat the butter on medium-high speed until it’s creamy and light in color.
Gradually add the powdered sugar, mixing on low speed and scraping down the sides after each addition.
Add the purées and food coloring, and beat until everything is well combined.
Once the cakes are cool, layer them with the frosting.