Meanwhile, brown ground beef in large skillet; remove from pan and drain. In same skillet, sauté garlic (and mush rooms) in olive oil. Return meat to skillet with mush rooms over low heat; add tomato sauce, pepper, and basil.
Dissolve cornstarch in 3 tablespoons milk; mix in remaining milk. Add to meat and stir over low heat until slightly thickened. Add processed cheese slices and stir until melted. Toss with hot pasta. Sprinkle generously with parmesan.
You can replace the penne with fusilli or elbow macaroni. Use just about any kind of cheese you want. Tex mex worked very well.