• Preheat oven to 350°F/177°C. Line a jelly roll pan with parchment paper. Set aside.

To make the cake batter

• To make the cake batter, in a large mixing bowl, combine 1 (13.25) ounce box, yellow cake mix, 3 large eggs plus 1 egg yolk, 1 cup whole milk, and ½ cup unsalted butter (melted) Whisk until smooth.
• Spread out the cake batter in the prepared jelly roll pan.
• Bake in the preheated oven for 12-15 minutes until a toothpick inserted comes out clean.
• Let the cake cool completely. While the cake cools, make the filling.

Prepare the filling.

• In a medium-sized mixing bowl using an electric mixer with beaters attached, beat 7 ounces marshmallow fluff, ¾ cup unsalted butter (room temperature), and 2 cups powdered sugar for 2 minutes.
• To the filling mixture, add 2 Tablespoons whole milk and whip until light and fluffy.
• If using a 10 x 15 inch jelly roll pan cut the cake in half. Spread the filling on half the cake and place the other half of the cake on top.
• If using a smaller baking sheet cut out the tree shapes and then slice the trees in half and spread with filling.
• Set your filled trees in the freezer to chill for 30 minutes.

How to make the frosting

• In a microwave-safe bowl, melt 1 pound white almond bark in 30-second intervals until smooth and melted, stir the white almond bark in between each interval.
• Carefully dip each tree into the chocolate, tapping off the excess and placing on a parchment paper lined tray.
• Immediately sprinkle with Green sanding sugar sprinkles.
• Repeat with all the trees.
• Melt 1 cup red candy melts in the microwave, using 30-second intervals until melted and smooth. Place the melted candy melts into a small plastic sealable bag with the corner snipped off.
• Pipe the red stripes onto the Christmas trees. Let the cake set for a few minutes.
• Ready to serve.