1. Preheat the oven to 200°C (400°F).
2. Cook the pasta in a saucepan.
3. In a bowl, flake the tuna with a fork.
4. Add the tomato paste, chopped shallot and garlic, as well as half of the sour cream. Mix well.
5. Season to taste with salt, pepper, and Italian herbs.
6. Once the tuna and tomato mixture is ready, spread it over the bottom of a baking dish.
7. Sprinkle with grated cheese (gruyère) and cover with the cooked pasta.
8. Cut the mozzarella into cubes and distribute it over the pasta. Add some Herbes de Provence and drizzle with the remaining sour cream.
9. Bake for about 20 minutes and serve.