1. Marinate the seafood in the zest and juice of ½ lemon, 1 tbsp olive oil, salt and black pepper.
2. Meanwhile, blend together all the ingredients for the pesto and season well to taste.
3. For the sauce, melt the butter over a gentle heat and whisk in the flour. Gradually add the milk, whisking continuously until the sauce thickens. Whisk in the crème fraiche, Parmigiano Reggiano cheese and lemon zest. Season to taste.
4. Cook the lasagne sheets in boiling salted water for 2-3 minutes and then keep warm.
5. Place the seafood and fennel on a hot griddle for 2 minutes, or until cooked.
6. To assemble, spoon a little white sauce onto the centre of each plate and top with a sheet of lasagne. Add more white sauce and top with seafood and fennel, followed by some walnut pesto. Repeat this layering process with another sheet of lasagne. Finally, top with another sheet of lasagne and drizzle over more pesto and drizzle over a small amount of olive oil before serving.
Recipe courtesy of Parmigiano Reggiano.