Homemade Copycat Little Debbie Christmas Tree Cakes

0 Preheat oven to 350°F and grease an 8×8 cake pan.
1 Prepare cake mix according to package instructions. Pour into the pan & bake 25–30 minutes, or until a toothpick comes out clean. Let the cake cool completely, then wrap tightly in plastic wrap and freeze overnight.
2 Make the Christmas tree shapes. Slice the cake horizontally through the middle to create two thin layers. Using a Christmas tree cookie cutter, cut out 12 trees. Place cutouts on a parchment paper lined baking sheet and freeze again while you make the frosting. If you're using store bought frosting, you can skip right to step 5.
3 Make the frosting. In a bowl, mix frosting ingredients with a hand mixer. Add milk 1 tablespoon at a time if it is too thick. Too thin, add more powdered sugar 1 tablespoon at a time.
4 Assemble tree cakes. Remove trees from freezer, frost one side, and sandwich to make 6 total cakes. Freeze again.
5 Make the chocolate coating. Melt white chocolate chips and coconut oil in the microwave in 10-second increments until smooth.
6 Coat the trees. Drop each tree into the melted chocolate and coat using two forks. Place back on parchment lined baking sheets and immediately add sprinkles. Let set.