Cook the first six ingredients 20 minutes. Strain and reserve 1 cup of the strained tomato mixture. Melt butter, add flour, and pour in slowly the tomatoes. When smooth, pour this over 3 well beaten egg yolks, and set aside to cool. Beat three whites very stiff and mix gently with tomato sauce, and bake in a moderate oven about 20 minutes. Grated cheese may be sprinkled over the top thickly before baking. Serve immediately.