PREHEAT oven to 350° F.
BEAT flour, oats, brown sugar and butter in a small mixer until crumbly. Press onto bottom on an ungreased 13 x 9-inch baking pan. Bake for 15 minutes.
BEAT pumpkin, evaporated milk, sugar, eggs, cinnamon, salt, ginger and cloves in a large mixer bowl. until smooth. Pour over crust. Bake for an additional 20 minutes.
COMBINE brown sugar and nuts in small bowl; sprinkle over filling. Bake for an additional 15 to 25 minutes or until knife inserted in center comes out clean. Cool completely in pan on wire rack. Refrigerate until ready to serve. Garnish with whipped cream if desired.