Cook gnocchi according to package directions. Once done, reserve and set aside about ¼ cup of the cooking water, then drain remaining water and set cooked gnocchi aside. Meanwhile, in a large skillet, heat butter and oil over medium-high heat. Add sausage, mushrooms, and onion and cook until sausage is just browned and vegetables are tender. Add asparagus and garlic and cook about 2-3 minutes.
Stir in wine and cook until liquid is almost evaporated. Add lemon juice, lemon zest, half of the basil, the red pepper flakes, salt, and pepper. Stir in cooked gnocchi and reserved cooking water. Mix until gnocchi are evenly coated with sauce. Serve with Parmesan cheese and remaining basil on top.