Rub the oil on to a grill pan, add the bacon and cook under a preheated medium grill for 5–7 minutes until starting to crisp. Add the tomatoes. Shake the pan to coat in the oil, season and return to the grill. Cook for 5 minutes or until the bacon is cooked through and tomatoes are lightly charred. Meanwhile, cook the pasta in a saucepan of salted boiling water according to the pack instructions until al dente.
To make the mascarpone mayonnaise, place the egg yolk and mascarpone together in a food processor and whizz together. With the motor still running, add the oil through the funnel, one small drop at a time, until you get a smooth mayonnaise-like sauce. Stir in the Parmesan and season.
Drain the pasta, reserving a little cooking water, and return to the pan. Stir through a little of the mascarpone mixture, followed by the rocket. Add a little cooking water to loosen if needed. Spoon into bowls, dollop over the remaining mayonnaise and top with the bacon slices and tomato.