First pre-heat the oven to 350F. Then line a 9 inch square pan with foil. Extending about 2 inches over the sides. Then grease the bottom only of the foil with cooking spray or shortening.
Next make the brownies as directed on the box. Cool fully about 1 1/2 hours. Then remove frm the pan by filling the foil sides carefully & peel away the foil. Then to cut the triangles shapes in the brownies, cut into 3 rows. Then cut each row into 5 triangles. Save the smaller pieces for snacking on later.
Then stirin the food coloring into the frosting. Then spoon the frosting into a small resealable palstic bag. partially seal the bag & cut off the tiny bottom corner of the bag. Then squeeze the bag to pipe frosting over the brownies. Then sprinkle with the decors.
Next break off the hooked part of the candy canes & insert the straight end into the bottoms of the triangles to make the tree trunks.