Put a pan of water on to boil, adding salt when it comes to the boil, and then cook the pasta according to the instruction on the pack.
Whisk together the tomato puree and milk, add the mascarpone then whisk again to combine.
In a large pan or wok warm the garlic oil and add the chilli flakes (if using). Stir then add the prawns and stir-fry for a minute or two (longer if frozen) until cooked through.
Pour in the vermouth and let it bubble up and reduce a little then add the pink sauce. Cook, stirring, until it is hot throughout, checking that the prawns are also cooked.
Drain the pasta and add it to the sauce, stirring to combine, before serving.
