1. Bring a large pot of salted water to a boil.
2. Add the rotini pasta and cook according to the package instructions until al dente.
3. Reserve about half a cup of pasta water before draining the pasta. Drain and set aside.
4. Heat 2 tablespoons of olive oil or butter in a large skillet over medium-high heat.
5. Add ground beef to the skillet, breaking it into smaller pieces with a spatula.
6. Cook the ground beef for 5-7 minutes until browned and fully cooked through.
7. Lightly season the beef with salt and pepper, drain excess grease, and transfer to a plate.
8. Reduce heat to medium in the same skillet and add another tablespoon of olive oil or butter if needed.
9. Add minced garlic to the skillet and sauté for about 30 seconds to 1 minute until fragrant.
10. Sprinkle all-purpose flour into the skillet and stir continuously for 1-2 minutes to cook the flour.
11. Gradually pour in the milk while whisking steadily to prevent lumps from forming.
12. Add grated Parmesan cheese and Italian seasoning into the skillet. Stir until the cheese is melted, and the sauce is thick and creamy.
13. Adjust the sauce thickness by adding a splash of reserved pasta water or milk if necessary.
14. Return the browned ground beef to the skillet, stirring to incorporate it into the sauce.
15. Fold in the cooked rotini pasta, ensuring the sauce evenly coats the pasta spirals.
16. Allow the mixture to simmer on low heat for 2-3 minutes to let the flavors meld together.
17. Remove the skillet from heat and garnish with freshly chopped parsley for added color and flavor.
18. Serve the dish warm, either on its own or paired with a side salad or garlic bread.