Preheat oven to 350 degrees F. Generously grease an 8x8 baking pan or 9 inch skillet with nonstick cooking spray. Set aside.

To make the topping: Combine the flour, oats, brown sugar, cinnamon and walnuts in a large bowl until well-combined. Pour in the melted butter and use your hands to combine until the mixture becomes crumbly and resembles wet sand. You may need to use your hands/fingers to form into nice crumbles. Cover the bowl with plastic wrap and place it in the fridge until ready to use.

To make the filling: place pears, maple syrup, cinnamon, vanilla and arrowroot starch in a large bowl and toss to combine. Take 1/3 cup of the topping mixture and toss with the apple mixture. Place the pear mixture in a prepared pan and sprinkle evenly with the remaining topping.

Bake the crisp on a baking sheet (just in case the filling bubbles over!) for 45 minutes-1 hour, or until topping is golden brown and filling is bubbling. Remove from the oven and cool for 10 minutes on a wire rack. Serve warm with your favorite vanilla ice cream or yogurt on top. Makes 9 servings.