Melt butter in a large saucepan over low heat, add marshmallows, and stir until completely melted.
Stir in green food coloring until the desired color is reached.
Remove from heat and stir in Rice Krispies until evenly coated.
Grease your hands with butter and shape about 1/4 cup of the mixture into a cone shape for each tree. Work quickly.
Press mini M&Ms into the sides as ornaments and place a star candy on top of each tree.
Sprinkle with green sanding sugar if desired and let cool completely on parchment.
