Mix together oatmeal, brown sugar, flour, salt and butter, then press half of mixture into 9x13-in. pan. Top with 4 c. diced rhubarb. Boil sugar, water and cornstarch until thick. Add 1 tsp. almond flavoring. Spoon 1 can cherry pie filling over rhubarb and liquid layers. Add remaining half of crust mixture with 1/2 c. nuts. Bake 45 minutes at 350-degrees.