Preparation
Melt butter in a heavy saucepan over medium heat.
Add milk and bring to a simmer.
Whisk in Cheez Whiz.
Gradually whisk in shredded cheese.
Stir until cheeses melt and mixture begins to bubble, about 5 minutes. Whisk in cayenne. Meanwhile, cook tortellini in a pot of boiling salted water until just tender, about 4 minutes. Drain.
Add tortellini to cheese sauce.
Toss to coat. Divide tortellini and sauce equally among pasta bowls and serve.