Preheat oven to 350°F. To make the shortbread crust: Cream butter and both sugars until light and fluffy. Mix in egg, then flour until combined. Press the mixture into a lined 8x8 baking dish. Bake for 22 minutes. To make the lemon filling: Whisk eggs until smooth. Add sugar and lemon juice, mix, then whisk in flour. Pour the filling over the baked crust. Reduce oven temperature to 325°F and bake for 35 minutes, until the center is just slightly jiggly. Cool at least 2 hours. Dust with powdered sugar & enjoy.
