Place a large pot of salted water over high heat to boil.
Place a large skillet over medium-high heat with 2 turns of the pan of EVOO, about 2 tablespoons, and 1/2-inch of water. Prick the sausages and place them into the pan. Cover and bring the liquid to a bubble, then reduce the heat to medium-low and simmer the sausages in the water until cooked through, 8-9 minutes.
While the sausages are working, place a medium saucepan over medium heat with the fennel fronds and cream. Bring the liquid up to a bubble and simmer until reduced by about half.
Drop the fettuccine into the boiling water and cook to al dente according to package directions. Once cooked, drain and reserve in the pot they were cooked in.