In a bowl, combine the flour and sugar; cut in butter until the mixture resembles coarse crumbs. Press into a greased 13x9-in. baking pan. Bake at 350° for 10 minutes. , Meanwhile, for filling, combine sugar and flour in a bowl. Whisk in cream and eggs. Stir in the rhubarb. Pour over crust. Bake at 350° until custard is set, 40-45 minutes. Cool. , For topping, beat cream cheese, sugar and vanilla until smooth; fold in whipped cream. Spread over top. Cover and chill. Cut into bars. Store in the refrigerator.