Prepare the cupcake batter according to the directions on the box. Line a muffin tin with cupcake liners, fill them about two-thirds full, and bake until a toothpick comes out clean.
Set the cupcakes aside to cool completely.
Line a cutting board or baking sheet with wax paper. Place plastic treat sticks spaced apart on the surface. Melt the green candy melts in a microwave-safe bowl in 15-second bursts, stirring in between, until smooth.
Transfer to a piping bag, snip the tip, and drizzle back and forth over each stick in a triangle shape to form trees.
While still wet, sprinkle on Christmas sprinkles. Refrigerate for 10–15 minutes to harden.
Repeat with the pink candy melts.
In a mixing bowl, beat softened butter until light and creamy. Gradually add powdered sugar, mixing after each addition.
Halfway through, add vanilla extract. If the frosting feels too stiff, add milk a little at a time until it’s fluffy but still firm enough to hold its shape.
Once the cupcakes are cooled, spread or pipe frosting onto each one.
Once the trees have set, gently press one candy tree into the center of each frosted cupcake. Serve and enjoy!