Start by preheating your oven to 350°F (175°C). This step is very important. A warm oven helps the casserole cook evenly. Grease your baking dish lightly with butter or oil so nothing sticks later.

Take a large bowl and add pineapple chunks. Pour in the reserved pineapple juice. Mix gently. This gives the dish a juicy base. Make sure the pineapple is well drained before adding.

In a saucepan, mix sugar and flour. Slowly add pineapple juice. Cook on medium heat. Stir often until the mixture thickens. It should look smooth and glossy. This will be your sweet sauce.

Pour the thick sauce over the pineapple in the bowl. Mix well. Then add shredded cheddar cheese. Stir until everything is combined. The cheese will melt later and add a rich taste.

Pour the mixture into your greased baking dish. Spread it evenly with a spoon. Make sure the layer is smooth. This helps the casserole cook evenly in the oven.

In another bowl, mix crushed crackers with melted butter. Stir until all crumbs are coated. This topping will become crispy and golden. It adds a nice crunch to the dish.

Sprinkle the cracker mixture evenly over the casserole. Cover all areas. This ensures every bite has that crispy topping. Press lightly so it sticks.

Place the dish in the oven. Bake for about 25–30 minutes. The top should turn golden brown. The edges will bubble slightly. That means it is ready.

Remove the casserole from the oven. Let it cool for 5–10 minutes. This helps it set properly. It also makes serving easier.