Prepare pasta according to package directions; drain then rinse under cold water until cool; drain again.
In a 2-quart saucepan, combine 2 1/2 cups of milk, the broth, vegetables, thyme, paprika and cooked pasta; bring to a light simmer (don't let it boil hard or the milk will separate!).
In a small bowl or cup, combine remaining 1/2 cup of milk with the cornstarch; stir mixture into the soup and bring to a simmer. Add clams; simmer, stirring frequently, for 3 minutes.
Add salt and pepper to taste. Serve hot.