Here is what I used to made these Christmas tree brownies.
Small baking cups work best.
Cut the tops off of the strawberries.
Use a small amount of frosting to hold the strawberry in place.
Use a decorating tube or bag to pipe frosting around the strawberry.
It is a good idea to start at the bottom.
You will get better at this the more you practice.
Use holiday sprinkles or candy to decorate your tees.