Instructions

Cut mozzarella into 1/2 inch cubes and allow to drain in a colander while preparing recipePlace fennel bulbs (whole) into a large pot and cover with cold, salted water by 1-2 inches and bring water to a boil

Once the water boils, lower and simmer until fennel is tender (should take 45-60 mins from when flame is first turned on), fennel should be cooked through but not mushy, remove from water and allow to drain and cool in a colander

While the fennel cools, cover the bottom of a large sauce pan with olive oil and turn heat to medium-high

Brown onion halves in oil on each side, once browned add tomatoes. Add 1/2 teaspoon salt, and freshly ground black pepper

Reduce heat to simmer and allow to cook for around 45 minutes, or until sauce is reduced and thick. Remove onion halves from sauce (you can use onion pieces in parmigiana if desired, I did not)

Once fennel bulbs are cooled, carefully take apart the bulbs, gently removing each layer, trying to keep each piece intact and place on paper towel to allow to continue drainingRemove sausage from casing and break into large chunks, brown sausage in a pan and allow to drain on a paper-towel lined plate

Preheat oven to 200oC/ 400 F

In a 9x13 roasting pan, add a thin layer of tomato sauce, followed by one layer of fennel pieces, more tomato sauce, a couple handfuls of Parmigiano Reggiano, followed by sausage and mozzarella cubes

Continue for two more layers, omitting the sausage on the last and final layer Place on center rack of oven and roast for 40 minutes, or until top is slightly brownedAllow to rest for 15 minutes before serving

This dish can be made ahead and reheated.