Begin by bringing a large pot of salted water to a boil. Add the bowtie pasta and cook according to the package instructions, usually around 8-10 minutes, until al dente. Drain the pasta, reserving about ½ cup of pasta water for later, and set aside.

In a large skillet, heat 1 tablespoon of butter over medium heat. Add the ground beef and cook until browned, breaking it up with a spoon as it cooks. Drain any excess grease and season with salt and pepper to taste.

In the same skillet, add the remaining 2 tablespoons of butter over medium heat. Once melted, add the minced garlic and chopped onion, and sauté until the onion becomes translucent, about 3-4 minutes.

Stir in the red pepper flakes (if using) and cook for another minute until fragrant.

Pour in the heavy cream, stirring constantly to combine. Allow the mixture to simmer for about 2-3 minutes, letting the sauce thicken slightly.

Reduce the heat to low and gradually stir in the shredded cheddar cheese and grated Parmesan. Continue to stir until the cheeses are fully melted and the sauce becomes creamy.

Add the cooked ground beef to the sauce and stir to combine.

Add the cooked bowtie pasta to the skillet, tossing to coat the pasta in the cheesy garlic butter sauce. If the sauce seems too thick, add some reserved pasta water a little at a time until you reach the desired consistency.

Taste and adjust seasoning with additional salt and pepper if necessary.

Garnish with freshly chopped parsley and serve immediately.