1. Cook the pasta according to the instructions on the pack. Whisk together 1 egg, 2 egg yolks, and the zested peel and juice of 1/2 lemon. Roughly chop the tarragon and stir it into the egg mixture. Add salt and pepper to taste.
2. When the pasta has cooked, strain off the water. Add the butter to the pasta pan and allow it to melt into the pasta. Add the egg and herb mixture and stir carefully. Grate the Jarlsberg® cheese over the hot pasta, turning it carefully so that the cheese is evenly distributed.
3. Serve with fresh-fried scampi or crayfish tails.