This recipe is taken from a recipe in Gourmet Magazine, August 1993. It has been modified very slightly, but is essentially their recipe. It was used for a booksigning with Karen Page and Andrew Dornenburg at The Spice House in Old Town, November 2008.
Preheat oven to 350.
Finely grind the almonds in a food processor with 1/4 cup of the confectioners' sugar and 1 cup of the flour. Add the butter and almond extract and blend until mixture resembles meal.
If not using a food processor, grind almonds in a mortar and pestle or coffee mill (well-cleaned to remove coffee flavor), stir in flour and confectioners' sugar, then cut in butter using a pastry knife or 2 table knives.
Pat the mixture into an 8 inch square baking pan and bake in the middle of the oven for 15-20 minutes, until it is pale golden. Let cool completely.
Beat the eggs until they are thick and pale. Beat in the granulated sugar and lemon juice and continue beating for 8 minutes. Sift in the remaining flour, baking powder, ginger, salt and stir until well-combined. Pour the filling over the cooled crust and bake 20-25 minutes, until the filling is set. Sift confectioners' sugar over it while hot and let cool before slicing.
When pressing the crust into the pan, try to give the edges a little height so the filling will be less likely to leak over them.