Cut the lower third of the watercress stems into small pieces. Rinse the leaves and tender stems, drain and clean thoroughly. Finely grind 30 g of watercress in a tall container with 70 ml of oil. Season with salt, pepper and 1 pinch of sugar. Roast pine nuts in a frying pan without fat until golden brown. Cut tomatoes into coarse strips. Finely dice shallots. Chop garlic cloves finely. Cut the ends of the asparagus spears into small pieces and remove the peel from the lower third of the spears. Cook asparagus in salted water for 3-4 minutes, rinse, drain well and cut diagonally into 2 cm thick pieces.
Cook pasta in boiling hot salted water according to package directions until al dente, pour into a colander and drain, reserving 300 ml pasta water. Heat remaining oil in a wide saucepan. Fry garlic, shallots, tomatoes and asparagus over high heat for 1 to 2 minutes, season with pepper, salt, chili flakes and sugar. Add pasta, pasta water and remaining watercress, mix well and pour into a preheated bowl. Serve with pesto, pine nuts and ricotta.
Concentrated and savory – ricotta salata Ricotta salata, or salted ricotta, is much firmer and more flavorful than the mild creamy variety. Well-stocked cheese retailers and Italian grocery stores carry it in bulk. You can also use sheep’s milk cheese as a substitute.