Preheat your oven to 350 degrees F. Spray the bottom of three 8-inch round cake pans with non-stick spray and then line with parchment paper. Lightly spray the paper too and then set the pans aside.
In a large mixing bowl, beat together the oil and sugar. Add the eggs, one at a time, with the mixer running on the lowest speed until the eggs are completely combined. Add the food coloring and the vanilla and mix until evenly combined.
In a separate mixing bowl, sift together the flour, cocoa powder, and salt - making sure there are no lumps. Set aside.
In a medium bowl, whisk together the buttermilk and baking soda. The milk will become slightly frothy.
Add half of the dry ingredients to the wet ingredients and mix. Then add the buttermilk mixture and mix. Add the rest of the dry ingredients and mix until smooth and combined. Scrape the sides of the bowl as needed. Divide the batter equally between the three prepared cake pans.
Bake the cakes for 28-30 minutes, or until a toothpick inserted in the center of the cake comes out clean and crumb-free. (see note)
Let the cakes cool in the pans for approximately 10 minutes. Then slide a knife around the edges of the pan and invert the cakes onto a wire rack to cool completely.
Once cakes are completely cool prepare the cream cheese frosting.
Place one cake layer on a cake stand or serving plate. Spread a generous amount of frosting over the layer all the way to the edges. Top with another layer and frost. Then place the last cake layer upside down so the flat bottoms side is facing up. Then frost the top and sides of the cake.
Decorated the cake as desired with sprinkles and/or white chocolate shavings. Refrigerate the cake until ready to serve. (I recommend letting the cake sit out for at least 15 minutes before serving if it's chilled.)
Notes
If you are using gel food coloring instead of liquid, start with a 2 teaspoons of gel coloring. Then mix into the wet ingredients and add more as desired to reach your preferred color.
If you're in a pinch, you can use store-bought cream cheese frosting (2 tubs), but the homemade frosting is SO much better!
If you don't have 8-inch cake pans, you can use 9-inch pans instead. If you are using 9-inch cake pans, bake for 22-25 minutes.
My cream cheese frosting recipe makes just enough to fill between the layers and frost the outside of the cake. If you want more frosting to use for decorating, make 1 1/2 batches of cream cheese frosting.