Thaw snow peas, cut in half. Peel the shallot, dice it finely and sauté it in the hot butter. Pour in the stock and cream, simmer for about 20 minutes without the lid. Boil the pasta, add the peas and snow peas in the last 5 minutes before the end of the cooking time. Chop the basil, add to the sauce. Season to taste with salt, pepper, lemon juice and zest. Fold the parmesan into the pasta and vegetable mixture.