Boil pasta in plenty of salted water for 10 minutes, drain and set aside
Preheat your oven to 160 fan/180
While pasta is cooking, fry off your onion and celery in a good glug of olive oil. Season with salt and pepper. Once the onion starts to go translucent, add in your fennel seeds and sausage meatballs .
When the sausage is cooked, add in your chopped garlic and tin of tomatoes and let it bubble away for about 10 minutes. If it starts to look dry, add in a little water.
Then stir through the spinach, then add in your pasta and transfer to a baking dish. Tear the mozzarella and dot around the top of the sausage pasta mix, and put in the oven for 30 minutes