Cook the pasta in a large saucepan of salted boiling water according to the pack instructions until al dente. Add the peas and asparagus 3 minutes before the end of the cooking time and cook until tender.
Meanwhile, mix together most of the grated lemon rind and the mascarpone in a bowl.
Drain the pasta and vegetables, reserving a little of the cooking water. Set aside the asparagus and keep warm, and return the pasta and peas to the pan. Stir through the lemon juice and oil, loosening with a little cooking water.
Season well and spoon into serving bowls. Sprinkle with the basil and the rest of the zest, top with the asparagus and serve with a dollop of the lemon mascarpone in each dish.