I love the contrast of the tart rhubarb and sweet haskaps, and the oatmeal crust is the perfect texture to balance it all out. I often adjust the sweetness level by using only maple syrup instead of brown sugar, and it still turns out great. When I make this crumble, I usually use a 9-inch pie pan, but sometimes I like to switch it up and make individual servings in ramekins. I also like to experiment with adding different spices like cinnamon or nutmeg to the crust for an extra layer of flavor. It's a versatile recipe that never fails to impress my family and friends.