Fill a large pot with lightly salted water and bring to a rolling boil; stir in tortellini and return to a boil. Cook uncovered, stirring occasionally, until the tortellini float to the top and the filling is hot, 6 to 8 minutes. Drain and transfer to a serving bowl.

Heat butter in a saucepan over medium heat; add garlic and cook until fragrant, about 3 minutes. Add pumpkin, evaporated milk, and chicken broth; bring to a boil. Lower heat and simmer, stirring occasionally, for 10 minutes. Stir Parmesan cheese and black pepper into pumpkin sauce.

Place peas in a microwave-safe bowl; heat in microwave into warmed through, 1 to 2 minutes.

Pour pumpkin sauce over pasta and top with peas.