Fill a star cookie cutter with softened butter; freeze. Using French toast, halve 4 diagonally. Arrange 3 whole pieces on a platter in a rectangle. Place 2 halves as treetop. Add remaining halves next to whole slices as branches. Sprinkle with green sanding sugar and confectioners' sugar. Place cooked bacon as trunk. Arrange colorful cereal garlands on top. Remove butter from cookie cutter and top tree.