For the baked langoustines
For the linguine
Preheat the oven to 200C/400F/Gas 6.
For the baked langoustines, place the langoustines onto a large piece of aluminium foil on a baking sheet. Drizzle with oil, squeeze over the lemon juice and wrap up the foil to completely seal. Transfer to the oven and bake for 10-15 minutes, or until completely cooked through.
For the linguini, heat the oil in a frying pan, add the shallot and garlic and fry until soft. Add the langoustine shells and heads and tomato purée and cook for 1-2 minutes.
Add the peppercorns, parsley stalks, lemon zest and white wine, bring to the boil and reduce the wine by half its volume.
Add 150ml/4½fl oz boiling water and cook to reduce the liquid again by half, then pass through a sieve into a large frying pan.
Add the double cream, bring to the boil, then reduce until the sauce has thickened and season, to taste, with salt and freshly ground black pepper.
Add the linguine and toss until well mixed into the sauce.
To serve, place the linguine in a large bowl with the baked langoustines arranged on top.