Preheat the oven to 350℉.
In a medium bowl, combine the crushed Ritz crackers, melted butter, and pineapple juice.
In a 9-inch baking dish, stir together the all-purpose flour, sugar and cheddar cheese.
Add the pineapple tidbits to the baking dish and stir to combine.
Spread the cracker mixture on top of the pineapple mixture in the baking pan.
Bake for 25 to 30 minutes, or until the casserole is heated through and the cracker topping is golden brown and crispy. Let cool slightly before serving.
