Cook tortellini according to package directions. Meanwhile, in a large saucepan, combine marinara sauce and cream. Gradually add flour and water until smooth. Bring to boil; cook and stir for 2 minutes or until thickened.
Add artichoke, thyme, and oil. Reduce heat; simmer, uncover for 3-4 minutes or until heated throughly.
Drain tortellini; toss with sauce.
Sprinkle with parmesan cheese, parsley and pepper.