You might be able to just use a rectangle cake shape, trim the corners to make an owl ish shape, and use the trimmings to make those little "ears" to either side of it's head. Frost with chocolate or white frosting, use a fork to make a feather look. A large cashew or more cake trimmings covered in beak-colored frosting for the beak. Half a marshmallow and flatten it to make big eyes. Chocolate for pupils.
Or make a tree from a rolled cake, and hollow out a knot hole for an owl figurine.