Cook pasta according to package directions. Drain; return to pan. Meanwhile, in a large skillet, cook sausage over medium heat until no longer pink, 4-6 minutes, breaking into crumbles; drain.
In a small saucepan, melt butter over medium heat. Stir in flour until smooth; gradually whisk in cream. Bring to a boil, stirring constantly; cook and stir until thickened, 1-2 minutes. Remove from heat. Stir in cheese, salt and lemon pepper. Add cheese sauce, sausage and spinach to hot pasta; toss to combine. Sprinkle with basil.