To make the Christmas tree toppers: Melt dark green candy melts according to package directions. Let cool enough to transfer to a piping bag and pipe, but don't let cool completely. On a baking tray lined with a silicon baking mat, place pretzel sticks about 1-2 inches apart. In a side to side direction, pipe the shape of a Christmas tree on top of the pretzel sticks. Immediately top with sprinkles and a yellow candy star. Place in the refrigerator for at least 10 minutes. When ready to use, lift each topper using an offset spatula.
To make the cupcakes: Preheat oven to 350 degrees F. Add flour, cocoa powder, baking powder, baking soda, and salt to a medium bowl and whisk to combine. In a separate mixing bowl, add 3/4 cups of butter and sugar and mix on medium-low speed to cream together. Add eggs, one at a time, and continue to mix. Add milk and 2 tsp. of pure vanilla extract. Add dry ingredients and continue to mix. Bring speed up to medium-high and continue to mix until combined well. Line cupcake tins with liners. Fill each liner 3/4 of the way to the top. Bake for 16-20 minutes, or until a toothpick inserted in the center comes out clean. Cool on a wire rack.
To make the frosting: Cream together 1/4 cups of butter and mascarpone. Add powdered sugar, 1 tsp. of vanilla extract and continue to mix until well incorporated.
To assemble the cupcakes: using an offset spatula, spread frosting on top of each cupcake. Sprinkle shredded coconut flakes on top and then insert Christmas tree toppers. Serve and enjoy!