Place popcorn in large bowl.
Place marshmallows and butter in medium saucepan over medium-lowheat. Stir until marshmallows are melted and mixture is smooth. Remove from heat.
Stir in vanilla extract.
Pour mixture over popcorn in bowl. Toss well to coat popcorn evenly.
Line a baking sheet with foil.
Spray hands with nonstick cooking spray, then scoop up about 1 cup of popcorn mixture.
Shape mixture into a cone shape, keeping the base flat. This forms the tree.
Sprinkle tree with decorating sugar; place tree on baking sheet.
Continue to make the rest of the trees.
Pipe frosting on trees to make a garland, then decorate them with colorful candies.