Mix together all dry ingredients (flour, sugar, baking powder, and salt) in a stand mixer with a paddle until fully combined. Mix chunks of room-temperature butter slowly into the dry ingredients; continue to mix until no large chunks of butter remain.

Pour in eggs and mix on low until just incorporated. Mix in the buttermilk on a low speed. Add in peppermint extract, and mix at a low speed until fully incorporated. Scrape down the sides of the bowl with a spatula, then beat on medium speed for about 30 seconds.

Divide batter evenly between three bowls; leave one white and mix the red gel color into the second and the green into the third. Transfer into your prepared cake pans (I find a kitchen scale helpful for this part). This guarantees your layers will bake to be the same height. Marble the colors together with a knife or small offset spatula.

Bake for 34-37 minutes (or until a toothpick comes out clean). Allow cake layers to cool for 10-15 minutes before removing from pans. Cool completely before frosting - set in the fridge or freezer to accelerate the cooling process if desired. (This is a great time to make your frosting!)

Once the layers have fully cooled, the caramelized bits can be trimmed from the sides / top of the cake using a serrated knife if desired. Be sure the layers are completely cooled or chilled before trimming. If you try to trim the layers while they’re still warm, they will crumble and break.

Beat together softened cream cheese and butter; slowly add in powdered sugar alternating with milk until frosting reaches desired consistency. Add peppermint extract and salt if needed and beat until well combined.

Remove about ¼ of the frosting from the bowl and mix in your red gel food color; repeat the process with the next ¼ of frosting and the green food color. You can mix colors together in your piping bags too if you’d like, or add a bit of gel color to the inside of a piping bag before adding white frosting for a fun swirled effect!

Once your cakes are cool, level them (if needed/desired). This can be done with a cake leveler or a large serrated knife and a ruler. Place a smear of frosting on your cake circle (to keep the cake from sliding while you decorate it) and center your first cake layer in the center of the circle. Spread the layer with frosting, and sprinkle a few Christmas nonpareil sprinkles over the frosting. Place your next cake layer on top, and repeat the process with your remaining cake layers.

Now you're ready to crumb-coat . If you're unfamiliar with crumb-coating, it's just what it sounds like – spreading a thin layer of frosting over the entire outside of the cake to keep crumbs out of your final layer. I usually do this with my large offset spatula.

Once your crumb coat has set (this takes about 5-10 minutes in the fridge), you’re ready to start piping!

Transfer colored frostings to large & small piping bags fitted with the tips of your choice – and pipe until the cake is covered! I usually pipe large swirls first, and then work my way back around with progressively smaller tips and patterns.

Add a few scattered sprinkles for a bit of texture; I thought angled silver rod sprinkles also added a fun look to the cake!

Stand back - congratulate yourself on your cake– and enjoy!