Preheat oven to 350 F.

For topping, to blender or food processor, add all topping ingredients except coconut oil and pulse until the mixture resembles coarse sand. Pulse in coconut oil until combined; the mixture will stick together when pressed between two fingers.

For filling, in large bowl, mix to fully combine all filling ingredients. Tip into 8 x 8-inch baking dish or 9 to 10-inch round baking dish, spreading fruit evenly. Distribute topping overtop of fruit loosely.

Bake for 40 to 50 minutes, until rhubarb is tender when pierced with knife, and filling is bubbling around edges. Cool for at least 15 minutes before serving.