Preheat oven to 350ºF. Lightly spray a 9x13-inch pan with cooking spray.
Drain the pineapple, reserving 1/2 cup of the juice. Place drained pineapple chunks in bottom of prepared dish. Combine flour and sugar and sprinkle over pineapple. Drizzle with reserved pineapple juice.
Sprinkle the cheese over the pineapple. Top with cracker crumbs. Drizzle casserole with butter.
Bake for 35 to 45 minutes, until bubbly and golden brown.