Cook Pasta:
Cook the bowtie pasta according to package instructions, adding salt to the water. Drain and set aside.

Brown the Beef:
While pasta cooks, heat olive oil in a skillet over medium heat. Add the ground beef and cook until browned, breaking it apart with a spoon. Drain any excess fat.

Sauté Onion and Garlic:
Add the chopped onion and minced garlic to the skillet with the beef. Cook until the onion is soft. Add Italian seasoning, red pepper flakes (if using), salt, and pepper. Remove the beef mixture from the skillet and set aside.

Make the Garlic Butter Sauce:
In the same skillet, melt the butter over medium heat. Add the minced garlic and sauté for 1 minute.

Create the Sauce:
Whisk in the flour and cook for 1-2 minutes. Gradually add the milk, whisking constantly. Bring the mixture to a simmer and cook until it thickens, about 3 minutes.

Add the Cheese:
Reduce the heat and stir in the shredded mozzarella and grated Parmesan cheese until melted and smooth.

Combine:
Add the cooked pasta and the beef mixture to the skillet. Toss everything to coat. If the sauce is too thick, add some pasta water to achieve the desired consistency.

Serve:
Serve the pasta with a garnish of fresh parsley and extra Parmesan cheese, if desired.