Preheat oven to 375°F.
To Prepare Topping: Combine all topping ingredients, except walnuts, in food processor container. Pulse on and off until mixture resembles coarse crumbs. Add walnuts and pulse 3 to 4 times to chop nuts; set aside.
In large bowl, combine filling ingredients; spray 9 x 13 x 2” baking pan with non-stick baking spray. Pour filling ingredients into pan and cover evenly with topping mixture.
Bake at 375°F for 35 – 40 minutes or until topping is browned. Cool slightly before serving.