Preheat oven to 350 degrees F and grease a 6-cup shallow baking dish (or a 9 inch round cake pan).
For the filling- in a large bowl stir the rhubarb and pears with the sugar, Strawberry Apple Rhubarb Jam, orange juice, cornstarch and spices until coated. Transfer the mixture into the prepared baking dish.
For the crisp topping-combine the flour, oats, brown sugar, cinnamon and salt in a medium bowl. Cut the butter in with a pastry blender, two knives, or by using your hands until uniformly blended and large crumbs form. Sprinkle the crumb topping over the rhubarb mixture.
Bake 40-50 minutes until the crumb topping is golden brown and crisp, the juices bubble and the fruit is tender.