To make Christmas tree brownies, start by preparing the brownie batter according to the recipe. Next, pour the batter into a baking dish and bake according to the directions. Once the brownies are cooked, let them cool completely before cutting them into triangular shapes using a large knife or a pizza cutter. To add the Christmas tree decorations, you can use sprinkles, chocolate chips, and other festive decorations. Finally, place the brownies on a platter and serve. Happy holidays!