Pineapple Crisp: The Perfect Pineapple Side Dish or Dessert

2 pounds pineapple chunks + any juice (see note)

3 Tbsp. corn starch

½ cup brown sugar

½ tsp. cinnamon

1/8 tsp. salt

2 Tbsp. butter

1 cup packed brown sugar

1 cup all-purpose flour

1 cup old-fashioned oats

1 Tbsp. cinnamon

11 Tbsp. salted butter (melted)