Heat the olive oil and butter in a large skillet.Add green peppers and cook for 2 minutes. Add remaining veggies, except tomatoes, and ham. Cook for about 5 minutes, until veggies are crisp tender.
Stir in chicken stock or wine, lemon juice and seasonings. Combine well.
Add milk and bring to a slow boil for 2 minutes, stirring frequently, just until the sauce begins to thicken up a bit. (It should just cover the back of a spoon without running off.)
Remove skillet from heat. Stir in tomatoes and cheese. Add pasta and toss to coat well. Garnish with additional shredded cheese, if desired.