For crumb mixture, combine graham cracker crumbs and granulated sugar; set aside.
Cut phyllo sheets in half crosswise. Spray the phyllo halves with cooking spray. Spread one-fourth of the crumb mixture on a phyllo half. Top with another phyllo half and another one-fourth of the crumb mixture; repeat with remaining phyllo halves and crumb mixture for a four-layer stack. Cut the stack into nine 2-3/4x4-inch rectangles. Cut each rectangle diagonally in half to form two triangles (18 total).
Coat a large baking sheet with nonstick cooking spray. Carefully place triangles on baking sheet. Bake in a 375 degree F oven for 6 to 8 minutes or until golden brown.
In a large skillet, melt margarine. Stir in brown sugar. Stir in apple slices, 3 tablespoons of the caramel ice-cream topping, raisins, brandy, cinnamon, and nutmeg. Cook, uncovered, about 5 minutes or until apples are tender, stirring occasionally.
To serve, place a strudel triangle on each of six dessert plates. Divide half of the apple mixture among the plates, spooning it atop strudel triangles. Place a second triangle over apple mixture, with points going in different directions than the first triangle. Top with half of remaining apple mixture. Repeat with remaining triangles and apple mixture.
Drizzle remaining caramel ice-cream topping over strudel triangles. Sprinkle with powdered sugar, if desired. Serve immediately. Makes 6 servings.
Prepare strudel triangles; store in an airtight container up to 3 days.