Gently bend each asparagus spear until it breaks naturally (Usually 1-2 inches in from the bottom). Discard the woody end, then slice remaining spear into thirds. Set aside.
In a saute pan over medium heat, add butter. Once melted, add onions. Cook for 3-4 minutes - onions will begin to brown and turn translucent. Add minced garlic and cook for 1 more minute.
Add bow tie pasta, vegetable broth, red pepper flakes, and pepper to pan. Scrape to deglaze pan as needed. Bring to a boil, cover, and reduce heat to low. Simmer for 9 minutes (or consult your pasta package directions and cook to al dente, minus 4 minutes).
Uncover, add asparagus, and stir to combine. Cover and simmer for an additional 4 minutes (for very thin asparagus, reduce time to 3 minutes. For very thick asparagus, increase time to 5 minutes).
Uncover pan. Most of liquid should be absorbed. Add heavy cream and parmesan cheese, stirring to combine. Cook for 2 minutes to heat through and allow cheese to melt.
Remove from heat and allow to set for 5 minutes before serving (sauce will continue to thicken as it stands).
Vegetable broth can be substituted with chicken broth or beef broth.
Butter can be substituted with olive oil.
If substituting bow tie pasta with another style of pasta, consult your pasta's cooking directions and adjust recipe times accordingly.