Cut each slice of bread diagonally in two. Spread butter thinly over each triangle, place, buttered side up, on a cookie sheet and lightly brown in the oven or broil very briefly.
Mix together cream cheese, mayonnaise, Tabasco, green onion and cayenne into a paste. Pile about 1 tablespoon on each triangle of bread on the unbuttered side. Sprinkle with Parmesan, about 1 teaspoon on each. Top each canape with 1/4 of a sun-dried tomato. Freeze.