Prepare the ravioli pasta dough. In a electric mixer with a dough hook, combine 1 egg, 6 yolks, pasta flour and a drizzle of olive oil. Then wrap in plastic wrap and let it for a rest for about 30 minutes in the fridge to allow the gluten to relax.
Prepare the langoustine filling. In a bowl mix together the chopped langoustine meat, 1 egg white, chopped tarragon, cream, salt and pepper.
Roll the pasta dough through the a pasta machine, 2 or 3 times, at its widest setting. Reduce the setting and roll the dough through again, 2 or 3 times. Continue until the dough is paper-thin, to about a 1mm thickness.
To make the raviolis lay the pasta dough out on a lightly floured surface then drop 2 tablespoons of the filling about 5cm (2 in) apart on one half the sheet of pasta, the mixture should make 6 to 7 raviolis. Fold the unfilled half over the filling. With your fingers, gently press out air pockets around each mound of filling and form a seal. Use a pastry cutter to cut each ravioli. Check to make sure the crimped edges are well sealed before cooking.
For the bisque of langoustine:
In a saucepan, heat the olive oil over a medium-high heat and slowly fry the onion, celery, carrots and garlic until the onion becomes soft. Add about two handfuls of the reserved langoustine heads along with some chopped fresh thyme and cook and stir for 5 minutes. Remove everything from the pan and set aside.
Pour the cognac into the same saucepan and scrape any bits from the bottom of the saucepan to de-glaze. Add the tomato puree and sprinkle in the flour then return the vegetable and langoustine head mixture to the pan then pour over the fish stock, reduce the heat to simmer and cook for 1 hour until reduced by about half.
Strain the stock through a fine sieve into a clean saucepan; discard the contents of the sieve. Add the cream and bring to the boil. Reduce the heat and and stir frequently until the bisque becomes the consistency of a sauce; season to taste. Keep warm over a low heat.
Shave the fennels through a mandoline as fine as possible. Season the fennel with a little vinaigrette dressing and add about half of the Espelette pepper, reserve the rest for later.
Bring a saucepan of salted water to the boil over a high heat. Add the ravioli and cook until the filling is hot and the pasta is al dente (you may wish to test the cooking time with a single ravioli before cooking a batch, cooking times may vary from about 6 to 12 minutes); drain.
To serve, divide the fennel between six warmed plates then lay the ravioli on top. Spoon over some of the bisque then finish with a pinch of reserved Espelette pepper and a sprinkling of fresh cress; serve immediately.
If you need more information, I will be very happy to help you: www.michel-bru.com