Add the butter to a large, heavy-bottomed stock pot set over medium heat. Once the butter has melted, add the garlic and a pinch of salt and cook, stirring, until fragrant, about 2 minutes.
Add the heavy cream and a pinch of black pepper and cook, whisking occasionally, until warmed through, about 3 minutes.
Reduce the heat to low, Stir in half the Parmesan cheese, then stir in the remaining Parmesan cheese until the sauce is smooth. Taste and season the sauce with salt and pepper.
Bring a large pot of salted water to a boil.
Add the chicken tortellini and cook until al dente, about 3 minutes (or according to package instructions).
Drain the tortellini then add it to the prepare sauce, stirring to combine. Serve immediately.