Fill a large pot with salted water and bring to a rolling boil. Add pasta and cook until al dente, about 8-10 minutes. Reserve 1 cup of pasta water, then drain.

In a large skillet, heat olive oil over medium-high heat. Add the beef, season with salt and pepper, and sear for 3-4 minutes until browned. Remove and set aside.

In the same skillet, reduce heat to medium, add butter, then onions. Sauté for 3 minutes until soft. Stir in garlic and cook for 1-2 minutes.

Pour in the chicken broth to deglaze the pan. After simmering for a minute, stir in heavy cream and add grated Parmesan cheese. Allow to thicken for 3-4 minutes.

Return cooked beef to skillet, add drained pasta, and toss to combine. Gradually add reserved pasta water if needed for creaminess.

Taste and adjust seasoning, then serve hot garnished with fresh herbs and extra Parmesan if desired.