1) In a large bowl, mix the first four ingredients together (flour, egg, salt and oil). Form a ball of dough using your hands, then let it rest for about 1 hour.In another bowl, mix together: ricotta, Gruyere and Parmesan cheese, eggs, parsley - then season with nutmeg, salt and pepper. Divide the dough into 2 equal parts.

2) Roll them out (using a rolling pin) to very make a large, thin rectangle.

3) Place tablespoons of filling on the sheet of dough about 1 inch apart until all the filling and dough have been used up. Using a pizza cutter, cut the ravioli in squares.Boil the chicken stock or water in a large pot, then add the ravioli and let it boil in the stock for about 3-5 minutes, until cooked.

4) Remove and drain the ravioli, then sprinkle melted butter and Parmesan cheese. Toss and serve hot.