TO MAKE THE PASTA, place the flour in a mound on a smooth work area, creating a well in the centre. Pour the 2 beaten eggs and 2 egg yolks into the well, and slowly pull the flour into the eggs until it is all incorporated. Finish kneading by hand, adding more flour if needed for a smooth consistency. Divide the pasta in half and roll out each half or feed through pasta roller until thin, number 6 setting on the machine. Roll out as many sheets of pasta as possible.
FOR THE SMOKED SALMON MOUSSE, puree the smoked salmon and 2 eggs together until smooth. Slowly add 1 cup cream, chopped chives and pepper. Mix thoroughly.
To assemble the raviolis, prepare a smooth, floured surface. Lay out the pasta and divide the smoked salmon mousse into 24 equal-sized portions and place these portions two inches apart on one sheet of pasta. Brush the beaten egg on the pasta between the mounds of salmon mousse, and cover with the other sheet of pasta. Cut raviolis apart, and refrigerate or freeze until you are ready to use.
Bring a large pot of lightly salted water to a boil, add raviolis, and cook about 6 minutes. Drain well.
Meanwhile, add to each of 8 fireproof plates 30g gruyere cheese and 1/8 cup cream. Heat under the broiler until the cheese melts then add the raviolis and sprinkle 30g more gruyere on top. Place under the broiler until the cheese browns lightly.