Peel the shallot and garlic, then finely dice them. Wash the carrot and celery, and finely dice them as well. Clean the mushrooms and pulse them in a food processor until finely chopped.

Heat the oil in a pot or deep skillet. Add the shallots, garlic, carrots, and celery, and crumble in the bouillon cube. Sauté the vegetables for 2–4 minutes, until the shallots are soft and translucent.

Add the ground beef, breaking it up well, and cook for 3–4 minutes until it becomes crumbly. Once the beef is nicely browned and crumbly, add the mushrooms and tomato paste, and sauté for 1–2 minutes. Then, deglaze with the water and strained/canned tomatoes.

Stir the uncooked pasta into the sauce. Cover and cook over medium heat for 12 minutes, stirring occasionally.

Season the one-pot dish with balsamic vinegar, Italian seasoning, salt, and pepper. Tear the mozzarella into small pieces and scatter them over the dish. Cover and cook over low heat for another 4 minutes, until the cheese has melted. Serve immediately.