I find it easy to pat the crust into the pan by covering the crust with saran wrap and patting into the pan,pushing the crust 1/4 inch or so up the side of the pan.
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Stir flour and powdered sugar with a fork,add butter until combined. Pat into a 9x 13 inch baking pan. Bake 15 mins. until light brown.
Beat remaining ingredients,pour onto crust,continue baking for 20-25 mins. or until filling is set. Cool. Sift powdered sugar on top. Cut into 1 1/2 inch bars.