Preheat the oven to 350°F (175°C). Drain the canned pineapple chunks thoroughly.

In a large mixing bowl, combine the pineapple, sugar, and flour, stirring until evenly coated. Gently mix in the shredded cheddar cheese.

Transfer the mixture into a greased casserole dish, spreading it out evenly.

Crush the Ritz crackers and mix with melted butter, then sprinkle over the top.

Bake for 25-30 minutes, until the topping turns golden brown, rotating the dish halfway through for even browning.