Preheat oven to 350°. Butter or spray and 9×11-inch baking dish (0r similar sized) with cooking spray.

In a medium bowl, mix together flour, sugar, and cheese. The flour will coat the cheese and help keep it from clumping together.

Add all of the pineapple to the bowl and mix well. Pour pineapple mixture into prepared dish.

In a small bowl, combine cracker crumbs and butter. Spread evenly on top of casserole. Bake for 30 minutes.