For the crust
Whip up the eggs and add to each egg 1 dessertspoonful of water. Dissolve the mustard in a little water; mix this, the cheese and seasoning with the eggs. Heat the butter in a frying-pan, and when boiling stir in the eggs and cheese mixture, stirring it with a knife over the fire until set. Turn the mixture into a bowl to cool. Meanwhile have ready the paste for the pastry. Rub the butter into the flour, add enough water to make it hold together, mixing the paste with a knife. Roll it out thin, line small patty pans, fill with the egg and cheese mixture. Moisten the edges of the paste in the patty pans, cover with paste, and press the edges together. Bake the little tartlets in a moderately hot oven until done; they will take from 15 to 20 minutes.