Cream all of the ingredients together and press the mixture into a buttered 8- x 8-inch square pan. Bake at 350° F for 20 minutes, until the crust is golden and slightly puffy.
While the crust bakes, mix the eggs, salt, sugar, and lemon juice together until combined.
Add the baking powder and flour to the egg mixture and mix well. Pour this mixture onto the hot bottom layer, then return to the 350° F oven for 30 minutes.
Cool completely and dust with confectioner's sugar before serving.
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