Preheat the oven to 350°F. Line a cupcake pan with liners.
To make the batter: In the bowl of a stand mixer fitted with the paddle attachment, add the butter, cane sugar, and vanilla extract. Mix on low until combined and there are no butter chunks.
Add the pumpkin, egg, and milk and mix to combine completely. Make sure to scrape down the sides of the bowl and mix to combine.
Add the cake flour, cocoa powder, baking powder, and sea salt in that order and mix to combine into a smooth batter. Be sure to scrape down the sides of the bowl and continue mixing until the batter is smooth and uniform.
Scoop the batter into the prepared cupcake pan, filling the liners three-quarters full.
Bake for 20 to 24 minutes or until a toothpick inserted in the center comes out clean. Allow the cupcakes to cool completely in the pan.
To make the frosting: In the bowl of a stand mixer fitted with the paddle attachment, add the butter, cream cheese, powdered sugar, and peppermint extract. Mix on low until combined and then speed mixer up to high and mix for 2 to 3 minutes or until the frosting is light and fluffy.
Add a small amount of frosting into 3 different bowls. This doesn’t have to be a lot, only a few tablespoons each is all you need. One of them can have even less (this one will be the chocolate one for the tree trunks).
Add the cocoa powder into the bowl with the least amount of frosting and stir to combine completely. Transfer to a piping bag with no tip, and just cut a small hole.
Add the matcha powder and strawberry powder to the other two bowls and stir to combine completely.
Fit one piping bag with Ateco tip #21 and add the green frosting. Add Ateco tip #6 to another piping bag and add the pink frosting.
Add the remaining bulk of the frosting into a piping bag fitted with Ateco tip #808. Line a baking sheet with parchment paper.
Pipe dollops of frosting onto each cupcake, this does not have to be perfect. Now, my favorite part is to turn over the cupcakes and press them onto the prepared parchment paper lined baking sheet. This will make the cupcakes flat and smooth.
Continue to do this with all the cupcakes, then place the baking sheet in the freezer for at least 30 minutes or until the frosting has set and you can easily pull the cupcakes off the parchment paper and you have a smooth top. If you find there area few holes in your frosting, run a cake spatula under hot water and use it to smooth the tops (see video).
Using either the green or pink frosting, pipe a zig zag triangle starting at the top of each cupcake and working your way down. Using the cocoa piping bag, pipe a small line for the tree trunk. You can also do rosettes or dollops with each color too, mix it up!
Decorate the tops of the trees with any sprinkles you like, this is the fun part, mix it up!
Make sure to store in the fridge.