Preheat oven to 350°. In a large bowl, combine the first five ingredients. Cut in butter until mixture resembles coarse crumbs. Stir in brown sugar. Add eggs and pumpkin; mix well.
Press into an ungreased 15x10x1-in. baking pan. Bake 20-25 minutes or until a toothpick inserted in center comes out clean. Cool on a wire rack.
For frosting, in a small bowl, beat cream cheese and butter until fluffy. Beat in the confectioners' sugar, vanilla and enough milk to achieve desired consistency. Spread over bars.