Make a pasta dough with flour, eggs and oil and let it rest for 20 min. For the bechamel sauce, sauté flour in hot fat. While stirring, gradually add the milk and make the sauce at low temperature for 10 min, stirring occasionally. Stir in crab butter. Season with salt, pepper and juice of one lemon.
For the filling, rinse and dry salmon fillet and cut into strips. Sprinkle with juice of one lemon. Cut cleaned fennel into strips. Finely dice garlic. Steam garlic and fennel in hot fat for 10 minutes until soft. Add crème fraîche and cheese and bring to a boil. Season to taste with salt and freshly ground pepper. Add salmon and basil cut into strips. Spread the bottom of an ovenproof dish with a little bit of béchamel sauce. Roll out the pasta dough in portions between cling film or with a pasta machine. Cut into rectangles (approx. 15×10 cm). Place 2 tsp. salmon filling on one side of each rectangle. Roll up dough pieces and place them seam side down in the mold. Spread remaining bechamel sauce evenly over top. Place mold in oven. Switch to 225 °C and bake for about half an hour.