1. Preheat the oven to 170ºC.
2. Beat the eggs thoroughly and add the milk, salt and pepper.
3. Slice the cooked potatoes and tomatoes.
4. Spray a pie dish with low calorie cooking spray. Add a layer of potato, then tomato, add a sprinkling of cheese and 2-3 tablespoons of the egg mixture. Layer again, finishing with a layer of cheese and pour over the remaining egg mixture.
5. Bake slowly in a moderate oven for about 40 minutes until set and the cheese topping is golden brown.
6. Garnish with parsley and serve.