Place the tortellini and broth into a large pot or Dutch oven.
Bring the mixture to a boil over medium-high heat.
Reduce the heat to medium-low, cover the pot, and simmer for 8 to 10 minutes, or until the tortellini is cooked through and most of the liquid is absorbed. Stir occasionally to prevent sticking.
Remove the pot from the heat. Stir in the heavy cream, pesto, Parmesan cheese, butter, and pepper until the sauce is smooth and creamy.
Heat gently for 1 to 2 minutes until warmed through, but do not boil after adding the cream.
Serve immediately.
Notes
If you prefer a thinner sauce, add a splash more broth or cream until you reach your desired consistency.
You can add pre-cooked chicken or spinach during the last few minutes of cooking for extra substance.