Pour the oil into a large frying pan, add the tomatoes and garlic and place over a very low heat. Leave the flavours to infuse for 5 minutes. If the garlic begins to colour, simply remove the pan from the hob and leave to infuse in the heat of the pan. Add the mascarpone and milk and stir until the mascarpone has melted. Remove from the heat and stir the herbs through the sauce. Season with salt and pepper.
Cook the pasta in a large saucepan of salted boiling water until it is al dente: according to the packet instructions for dried pasta or for 2 minutes if using fresh pasta. Drain thoroughly, reserving a ladleful of the cooking water.
Return the frying pan with the sauce to a low heat and gently toss in the pasta and Parmesan until well coated. Add some of the reserved pasta cooking water to loosen the sauce to a silky consistency. Serve immediately with some grated Parmesan on the side.