To prepare the crust, beat 1/4 cup granulated sugar and the butter at medium speed of a mixer until creamy. Lightly spoon 1 cup flour into a dry measuring cup; level with a knife. Gradually add 1 cup flour to sugar mixture, beating at low speed until mixture resembles fine crumbs. Gently press mixture into bottom of an 8-inch square baking pan. Bake at 350° for 15 minutes; cool on a wire rack.
To prepare topping, beat eggs at medium speed until foamy. Add 3/4 cup granulated sugar and next 5 ingredients (3/4 cup granulated sugar through salt), and beat until well-blended. Pour mixture over partially baked crust. Bake at 350° for 20 to 25 minutes or until set. Cool on wire rack. Sift powdered sugar evenly over top.