Lemon Bars with Bisquick Crust

Preheat oven to 350 degrees F. Combine Bisquick, sugar, salt, and butter in a large bowl. Blend together with a spatula or wooden spoon until smooth and well mixed. Line an 8- by 8-inch baking pan with parchment, so that paper hangs over the edges (you'll use this to lift the bars out once done). Press crust into pan on top of parchment in an even layer. Bake crust about 15 minutes, or until just beginning to brown. Turn oven temperature down to 325 degrees F. Make the filling by beating eggs, yolks, lemon zest and juice, salt, and flour with an electric mixer until smooth and combined. Pour filling into crust and bake at 325 degrees F for another 20 minutes. Let bars cool down to room temperature, then chill in pan at least 1 hour. When ready to serve, remove bars from pan using parchment overhang, cut into bars, and dust tops lightly with confectioners' sugar.