Preheat oven to 425 degrees F (220 degrees C).Advertisement
In a large bowl, combine the spinach, feta cheese, mozzarella cheese, processed cheese food, 1/2 the butter, vinegar, garlic powder, salt and pepper. Mix well and set aside.
Place a layer of phyllo dough into the bottom of a lightly greased 2-quart casserole dish. Spread the spinach and cheese mixture into the dish and top with 4 layers of phyllo dough, spraying each layer with butter-flavored cooking spray. Drizzle the remaining butter over the top.
Bake at 425 degrees F (220 degrees C) for 20 minutes.
Reynolds® Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.