Cook the pasta in salted water according to the instructions on the packet.
In the meantime, put the tuna and the oil in a large bowl and lightly tear it apart with a fork. Add the pesto and mix in. Add about a third of the cheese and stir in. Wash the cherry tomatoes and cut in half.
Preheat the grill.
Drain and drain the pasta. Mix with the tuna mixture and cherry tomatoes, season with salt and pepper. Put everything in a baking dish, sprinkle with the remaining cheese and bake under the grill for about 5 minutes until the cheese has melted.