Almond Coffee Cake

Grease round baking dish. Heat oven to 375 degrees. Beat egg yolks with lemon peel until foamy, add half of ground almonds. Beat egg whites until stiff, add sugar and beat until very stiff. Put egg white mixture on egg yolk mixture and add rest of ground almonds. Mix everything carefully. Pour into baking dish and bake on second rack from bottom for 35-40 minutes. Do not open door during first 20-25 minutes. Let cool for 2 hours.