½ cup olive oil, divided
1 pound sweet Italian fennel sausage, removed from casing
8 ounces pancetta, ¼-inch diced
1 head fennel, thinly sliced, fronds chopped for garnish
1 medium onion, peeled, chopped
3 cloves garlic, peeled, sliced
3 tablespoons fennel seed, toasted
3 cups fresh breadcrumbs
1 cup turkey stock or chicken stock
1 whole turkey (about 12 pounds), boneless, skin-on
2 tablespoons fresh thyme leaves
2 tablespoons sage leaves, chopped
3 tablespoons fennel pollen or ground fennel seed, divided
6 stalks celery, for roasting
Kosher salt and freshly ground black pepper, to taste
Preheat oven to 450 degrees F.
Heat a large sauté pan with 2 tablespoons olive oil over medium-high heat. Add the sausage and pancetta and cook until browned, about 7 minutes, breaking up the sausage with the back of a spoon. Add the onion, sliced fennel, garlic and fennel seed and cook until almost softened and lightly browned, about 10 minutes. Remove to the large bowl with the bread crumbs add the stock and stir to combine. Season with salt and pepper and allow to cool slightly.
On a clean work surface, place the turkey skin side down. Lay plastic wrap on top and using a meat mallet pound the turkey to even thickness and shape. Remove the plastic wrap and discard. Season on both sides with salt and pepper.
Lay sprigs of thyme and sage in the center of the turkey and top with bread mixture, leaving a 1-inch border on all sides. Starting from the long side, roll it up like a jelly roll and tie with twine. Brush the roll all over with olive oil, sprinkle half of the fennel pollen over it and season with salt and pepper.
Arrange celery on the bottom of the roasting pan.
Remove turkey to the roasting pan and place skin side up on celery, and drizzle with more olive oil. Roast in the oven for 1 hour 45 minutes or until the internal temperature in the thickest part reaches 155 degrees F.
Remove the turkey to a cutting board and allow to rest for 20 minutes. Season the outside of the turkey with remaining fennel pollen. Remove the twine and carve into ¾-inch thick slices.
Garnish with fennel fronds and finish with a drizzle of olive oil.