In a medium bowl, stir together the undrained crushed pineapple, sugar, and flour until combined.
Fold in the shredded cheddar cheese and 2 tablespoons of the melted butter. Mix until the cheese is evenly distributed.
Grease a 10-inch cast iron skillet or line it with heavy-duty aluminum foil (for easy cleanup). Pour the pineapple mixture into the skillet and spread it evenly.
In a small bowl, combine the crushed crackers with the remaining 6 tablespoons of melted butter. Stir until the crumbs are fully coated. Sprinkle the buttery crumb mixture evenly over the pineapple layer.
Cover the skillet with a lid or a sheet of foil. Place it on a camp stove over medium-low heat. Cook for 20 minutes, then remove the lid and cook for another 5 minutes to let the topping crisp. If using a fire, see the FAQ for timing.
Remove from heat and let it rest for 5 minutes before serving. The casserole will be bubbly and golden. Spoon it out warm as a side to grilled sausages, pork chops, or even breakfast pancakes.