In the meantime, cut the tomatoes and mozzarella into small cubes. Mix in a bowl with the olive oil and 2 tablespoons of pesto and let it steep until the pasta is cooked.
Drain the pasta and put it back in the saucepan. Add the tomato and mozzarella mixture to the warm pasta, mix and season with the rest of the pesto. If you leave the pot on the warm stove for 1-2 minutes, the mozzarella will melt.
If you like, you can also add a little torn basil leaves.