Preheat the oven to 350 degrees F. Sprinkle a 9-inch baking dish with a cooking spray.
Peel and cut into slices with a knife (chop in a blender) fresh pineapple. Or drain the juice from canned pineapple and chop. Leave 1/4 cup juice.
Combine flour, sugar, grated cheese, chopped pineapple, and 1/4 juice. Stir with a spoon and put in a mold.
Grind the cracker in a blender and combine with melted butter. Put the cracker mixture on top of the casserole, squeeze a little with your hand.
Bake in the oven for half an hour. Serve hot.