Cook the Tortellini: Bring a large pot of salted water to a boil. Add the tortellini and cook according to the package instructions (usually about 3-5 minutes). Drain and set aside.
Make the Garlic Butter Sauce: In a large skillet over medium heat, melt the butter. Add the minced garlic and sauté for 1-2 minutes until fragrant. If using, stir in the crushed red pepper flakes for a hint of spice.
Combine Tortellini and Sauce: Add the cooked tortellini to the skillet and toss to coat in the garlic butter sauce. Cook for 2-3 minutes to allow the flavors to meld together.
Add Finishing Touches: Remove the skillet from heat. Stir in the grated Parmesan cheese and sprinkle with fresh parsley. Season with salt and black pepper to taste.
Serve: Serve warm and enjoy as a main course or alongside your favorite protein.