Season your chicken pieces with salt and black pepper. In a large pot over medium-high heat, melt butter until bubbly. Add chicken to the pot and cook for about 6–8 minutes, stirring occasionally until browned and fully cooked through. Remove the chicken from the pot and set it aside.
In the same pot, add a bit more butter if needed, then sauté the minced garlic until fragrant—about 30 seconds. Stir in the crushed red pepper flakes.
Pour in chicken broth while scraping up any bits stuck to the bottom of the pot. Stir in heavy cream and bring to a gentle simmer.
Add fresh tortellini to your simmering sauce. Cook for approximately 4–6 minutes until they are tender and heated through.
Return the sautéed chicken to the pot and add grated Parmesan cheese. Stir until melted and combined, then let it cook together for an additional 2–3 minutes before serving.