In a medium bowl, combine the flour, brown sugar, pecans, oats, cookie crumbs, and cinnamon. Using a fork or pastry cutter, cut the softened butter into the dry ingredients. Once halfway incorporated, use your hands to squeeze the ingredients together, until a moist crumb forms; set aside.
Make the Filling:
Preheat the oven to 350ºF, and spray a 9-inch baking dish with nonstick cooking spray.
Combine the strawberries and rhubarb in a large bowl.
In a separate bowl, whisk both sugars, cornstarch, cinnamon, and salt together. Stir dry mixture into the fruit mixture. Pour the filling into the baking dish.
Evenly crumble the crisp topping over the filling. Bake for 35-40 minutes, or until bubbly and golden brown on top.
Allow the crisp to cool for at least 30 minutes before serving. Leftover crisp can be stored covered in the refrigerator for up to 5 days.
Notes
*The Biscoff cookie crumbs can be substituted with 1/2 cup graham cracker crumbs or whole oats.