Preheat oven to 180 degrees.
Unroll the croissant roll dough and separate into 8 triangles.
Place the triangles on an ungreased baking sheet.
Brush the triangles with melted butter, then sprinkle with garlic powder and dried parsley.
Fold the straight end of each triangle over to resemble the brim of the witch hat.
Bake for 10 to 12 minutes or until hats are golden brown.
While the hats are baking, cut the slice of cheese into eight thin strips.
Remove the witch hats from the oven. Allow to cool slightly, then place a strip of cheese on each hat above the brim, trimming the cheese to fit the hat.
Place an olive slice in the center of the cheese strip to resemble the buckle. Allow the cheese to melt slightly to secure it in place before serving.
Serve with tomato sauce for dipping (optional).