Preheat oven to 400 degrees. Arrange prosciutto slices vertically side by side on a cutting board, overlapping each by 3/4 inch. Place turkey, skin side down, on the prosciutto slices, with wings at top and legs at bottom. Arrange turkey tenders at each side to fill in the space between the wings and legs.
Sprinkle turkey with 2 tablespoons salt, including the back side of the tenders and under any other loose pieces of meat. Sprinkle garlic, fennel fronds, fennel seeds, rosemary, sage, and fennel pollen evenly over turkey. Arrange turkey so there are no separations (turkey should be in one even layer).
Starting from the bottom, roll turkey tightly with prosciutto, keeping prosciutto in place (see photo, below). Tie together with kitchen twine at 3-inch intervals.
Heat oil in a large skillet over high heat. Brown rolled turkey on all sides, about 8 minutes. Transfer to a roasting rack set on a large rimmed baking sheet or in a roasting pan. Roast until an instant-read thermometer inserted into center reaches 165 degrees and juices run clear, about 50 minutes. Let rest for 10 to 15 minutes. Serve with gravy.
Fennel pollen can be purchased at kalustyans.com.