Bring a large pot of salted water to a boil. Add the gemelli pasta and cook according to package instructions until al dente. Reserve 1/2 cup of pasta water, then drain the pasta and set aside.

In a large skillet, heat the olive oil over medium heat. Add the Italian sausage, breaking it up with a spoon, and cook until browned and cooked through, about 5-7 minutes.

Add the minced garlic to the skillet and sauté for about 1 minute until fragrant.

Stir in the asparagus pieces and cook for an additional 3-4 minutes until they are tender but still crisp.

Pour in the chicken broth and red pepper flakes (if using), bringing the mixture to a simmer. Cook for 2-3 minutes to allow the flavors to meld.

Add the cooked gemelli pasta to the skillet, tossing to combine. If the mixture seems dry, add reserved pasta water a little at a time until desired consistency is reached.

Season with salt and pepper to taste. Remove from heat and stir in the grated Parmesan cheese.

Serve immediately, garnished with fresh parsley.