Combine flour, oats, 1/2 cup brown sugar and butter in small mixer bowl. Beat at low speed for 1 to 2 minutes or until crumbly. Press on bottom of ungreased 13 x 9-inch baking pan.
Bake for 15 minutes.
Combine granulated sugar, pumpkin, evaporated milk, eggs and pumpkin pie spice in large mixer bowl. Beat at medium speed for 1 to 2 minutes; pour over crust.
Bake for 20 minutes. Combine pecans and remaining 1/4 cup brown sugar in small bowl. Sprinkle pecan topping over filling. Continue baking for 15 to 25 minutes or until knife inserted in center comes out clean. Cool completely in pan on wire rack. Cut into bars. Top with whipped cream.