For crust, in a medium bowl, combine 1 cup flour and the 3 tablespoons granulated sugar. Using a pastry blender, cut in the 1/3 cup butter until mixture resembles fine crumbs and starts to cling. Pat butter mixture into the bottom of an ungreased 9x9x2-inch baking pan.
For filling, in a large mixing bowl, beat the 1-1/4 cups granulated sugar and the 3/4 cup butter with an electric mixer on medium speed until combined. Beat in corn syrup and egg just until combined.
Alternately add 1 cup flour and evaporated milk to beaten sugar-butter mixture, beating on low speed after each addition just until combined (batter will appear slightly curdled). Pour over crust in pan. Spread batter evenly to edges of pan.
Bake in a 350 degree F oven about 35 minutes or until cake is nearly firm when gently shaken. Cool in pan on a wire rack. If you like, sprinkle with powdered sugar before serving. Makes 12 servings.