Cake:

1. Preheat oven to 350˚F/180˚C. Grease three 8" cake pans and lightly dust with cocoa powder or line with round parchment paper sheets.
2. In a large mixing bowl, stir together gluten free flour, oat flour, cocoa powder, baking powder, baking soda and salt.
3. Using a stand mixer or hand mixer, cream butter and sugar until light and fluffy (about 1 minute). Add in vanilla and peppermint extract. Add applesauce and maple syrup and continue mixing. (Note: the mixture may look separated but this is common with vegan butter – it will come back together when you add dry mixture).
4. Stir espresso into oat milk. Melt chocolate in microwave in 30 second intervals and set aside.
5. Alternate adding dry mixture and oat milk mixture into wet ingredients, mixing on medium-low until fully incorporated. Add in melted chocolate and mix until smooth. Using a spatula, stir in crushed candy canes.
6. Divide batter between the three cake pans (about 710g/9oz of cake batter per pan if using a scale) and smooth with a spatula. Bake for 32-34 minutes, until a toothpick comes out clean.
7. Remove from oven and let cool completely before frosting.

Buttercream and assembly:

1. Add softened butter to a stand mixer and cream at medium-high speed until light and fluffy (about 1 minute). Slowly add in the powdered sugar, mixing well between each addition, until frosting is stiff, but still light.
2. Add in vanilla and peppermint extract, and 3 tablespoons of milk. Beat on medium-high for 10-20 seconds. If it's too stiff, add in another 1-2 tablespoons of milk.
3. Transfer about 1/3 of the buttercream into a separate bowl and stir in red food coloring. Leave the other 2/3 white.
4. To create striped interior, pipe white and red frosting in a concentric circle on top of the bottom and second layer.
5. Frost the cake with a crumb coat of white frosting. Add a few dollops of red and white frosting around the sides of the cake, then use a cake scraper to smooth it out to create a watercolor effect.
6. For the red and white peppermint swirls on top, pipe white and red frosting next to each other on a piece of plastic wrap. Roll it up gently, then transfer to piping bag with a swirl piping tip. Pipe on to top of cake, then garnish with crushed candy canes.