Tagliatelle with Prawns, Asparagus and Coconut Milk

Pasta with prawns and asparagus is a classic served all over the world - we all know that. But there is nothing common about this dish, a version of which I ate at Terzetto, a traditional Italian restaurant in Rio. The twist - done Brazilian style - is the coconut cream sauce, infusing the prawns and asparagus with a nutty aroma and richness. I like to make my own prawn stock by roasting the shells with an onion, about 2 garlic cloves and a tablespoon of tomato purée, but any chicken or fis