Preheat the oven to 350 degrees F.
In the bowl of a stand mixer, cream together butter, oil, and sugar.
Add in eggs and vanilla and beat until light and fluffy, for a couple minutes.add
Then add in the yogurt and mix until combined.
After you mill your flour, pour it through a sifter and sift until most of the bran is left behind. You should have 325 grams after it has been sifted.
In a medium bowl, mix together flour, baking powder, baking soda, and salt.
Working in batches, add ⅓ of the flour mixture into the batter, then half of the buttermilk, mixing well between each addition. Repeat, and end with adding in the last of the flour.
Pour cake batter into a rimmed baking sheet lined with parchment paper in a thin layer. You can use either a large baking sheet (about 13 x 18), or two smaller baking sheets.
Bake for 17-20 minutes.
Allow the cake to cool.
Using a Christmas tree cookie cutter, cut out Christmas tree shapes while the cake is still in the pan.
Use a spatula to remove the trees from the pan.
If the trees are too thick, you can use a knife to cut a little bit off the backs of them.
To make the icing, beat together butter, powdered sugar, milk, and vanilla until fluffy and smooth. Make sure the icing is not too runny.
Put the icing in a ziploc bag or a piping bag and pipe the icing onto half of the trees. Put the rest of the trees on top of the iced trees to make the cakes.
Place the cakes on a baking sheet lined with parchment paper and freeze for one hour.
Once the cakes have frozen, melt the white chocolate chips and coconut oil in a medium bowl in 15-30 second increments in the microwave. Be careful not to burn the chocolate!
To coat the cakes, take one tree cake and place it on a large fork. Holding over the bowl of chocolate, use a small measuring cup to dip into the melted chocolate and pour the chocolate over the cake while it is on the fork. Continue pouring the white chocolate over top of the cake until it is fully covered in chocolate.
Place the cakes on a baking sheet lined with wax paper or parchment paper.
Before the cakes harden, top with green sugar sprinkles.
Place in the fridge until the white chocolate has hardened.
Prepare the red icing by combining the powdered sugar with desired amount of food coloring. If using gel, you may need to add some milk to make it more runny.
If using a powder coloring that mixes into water, you can just mix it with the powdered sugar. You want a thick consistency that is not too thick to squeeze out of a small hole. Just add more or less powdered sugar to get the right consistency.
Pour the icing into a plastic bag and ice the trees with four stripes each.
Place back in the fridge until hardened.