Preheat oven to 350°F and line a jelly roll pan with parchment paper.

In a large mixing bowl, combine cake mix, eggs + yolk, milk, and melted butter. Mix until smooth.

Spread batter evenly in the prepared pan and bake for 12–15 minutes or until the center is set. Cool completely.

In a medium bowl, mix marshmallow fluff, softened butter, and powdered sugar. Add milk and whip until fluffy.

Lift the cooled cake from the pan and cut in half. Spread filling over one half and place the other half on top.

Use a Christmas tree cookie cutter to cut out cake sandwiches. Place trees on a parchment-lined tray and freeze for 30 minutes.

Melt almond bark in 30-second intervals at half power until smooth.

Dip each chilled tree into the melted coating, letting excess drip off. Add green sprinkles immediately before it sets.

Melt red candy melts the same way. Transfer to a zip-top bag, snip the corner, and drizzle stripes over each tree.

Let the coating harden completely, then enjoy!