Boil whole lemons in plenty of water for 2 hours. Cool, remove seeds, and chop very fine. Preheat oven to 350F. Beat egg yolks till frothy. Slowly add sugar, chopped lemon, and almonds. Beat egg whites until stiff. Gently fold the egg whites into the egg yolk mixture. Grease a 9 x 13″ cake pan. Pour mixture into pan. Bake about 40 minutes or until lightly brown (keep a close eye on these and check them frequently.) Check for doneness by inserting a wooden pick, which must come out clean. When cool, cut into 3-inch strips and dust with powdered sugar.