Sprinkle the buttery cracker mixture evenly over the pineapple layer, covering it from edge to edge so you get a crispy bite in every spoonful.
Bake the casserole in the preheated oven for 25–30 minutes, or until the topping is golden brown and crisp and you can see the pineapple and cheese mixture bubbling up around the edges.
Remove from the oven and let the casserole rest for about 5–10 minutes before serving. This helps it set up a bit while still staying warm and gooey. Serve scooped onto plates so you can see that bubbly fruit, melted cheese, and crispy cracker topping all together.
For families with picky eaters, you can swap pineapple chunks for pineapple tidbits or crushed pineapple so there aren’t big pieces of fruit—kids often like the smoother texture. If you prefer it a little less sweet, cut the sugar down to 3/4 cup or even 1/2 cup, especially if your pineapple is very sweet. For more of that sweet-and-savory contrast, use extra-sharp cheddar or mix in a bit of white cheddar with the yellow. If you only have salted butter, you can still use it; just know the topping will have a slightly saltier, snacky flavor that many people love. To make it ahead, assemble the pineapple, sugar, and cheese in the dish, cover, and refrigerate up to a day. Wait to mix and add the cracker-butter topping until just before baking so it stays crisp. You can also double the recipe and bake it in a 9×13-inch dish for big gatherings—just keep an eye on the baking time and add 5–10 minutes if needed until the top is deeply golden and the edges are bubbling.
