Preheat the oven to 350 degrees. In a food processor, combine the flour, almonds, lemon zest, confectioner's sugar and butter. Process until a dough forms and press into a lightly buttered 13 x 9 inch pan, forming a 1/2 inch rim which goes up the sides of the baking pan. Bake for 20 minutes or until partially baked. Remove from oven to cool on a rack. Combine the eggs, sugar, flour, baking powder, grated lemon zest, and juice. Pour the lemon mixture over the cooked dough and spread it evenly. Return the baking pan to the oven and bake for another 15 to 20 minutes or until the filling is set, top is barely browned around edges. Cool to room temperature. Cut into bars and set a candied violet in the middle of each bar.