The original recipe calls for a full cup of sugar but I find that it's sweet enough with half the amount. After all, you will get plenty of sweetness from the pineapple.
Preheat oven to 350 F. Spray a medium size casserole dish with cooking spray (I use an oval casserole dish that is about 2.5 quarts).
Place the shredded cheese in a large bowl. In a smaller bowl, combine the flour and sugar and toss with cheese until combined. Stir in the pineapple and pour into casserole dish.
Combine the reserved pineapple juice, crackers and melted butter and spread over pineapple-cheese mixture.
Bake uncovered, for 25-30 minutes or until top is golden brown. Serve warm.