Preheat the oven to 350 degrees F (175 degrees C). Grease a medium casserole dish. Mix sugar and flour together in a large bowl. Gradually stir in cream cheese. Add drained pineapple chunks and stir until well combined. Combine reserved pineapple juice, butter, and cracker crumbs in a medium bowl. Spread crumb mixture over the bottom of the casserole dish to make a crust. Pour pineapple mixture over crust and top with Cheddar cheese. Bake in the preheated oven until golden brown, 25 to 30 minutes.