Preheat oven to 350 degrees. Grease a medium-size casserole dish with butter.
In a large bowl, stir together the sugar and flour. Gradually stir in the cheese. Add the drained pineapple chunks, and stir until ingredients are well combined. Pour mixture into prepared dish.
In another bowl, combine cracker crumbs, melted butter, and reserved pineapple juice. Stir with a rubber spatula until blended. Spread crumb mixture on top of pineapple mixture. Bake for 25-30 minutes or until golden brown.