Beat the vanilla frosting and marshmallow crème with an electric mixer until well combined. Dye the frosting a vibrant green colour.
Place in a piping bag fitted with a small star-shaped piping tip.
Remove the pots from the fridge and pipe a tall dollop of frosting on top of each pot. Starting at the base and working upwards, pipe star shapes and create a pine tree. Decorate with sprinkles.
Return the pots to the fridge and chill for 30 minutes.