Fill a large pot with salted water and bring it to a boil. Add the penne and cook until al dente following the package directions. Drain and set aside.

Heat the olive oil in a large skillet over medium heat. Add the diced onion and cook until softened, about 3 minutes.

Add the minced garlic and cook 1 minute, stirring, until fragrant.

Add the ground turkey to the skillet. Season with kosher salt and black pepper. Break the meat into small pieces and cook about 6 minutes, until browned and no longer pink.

Pour in the chicken broth and half-and-half. Stir well and scrape any browned bits from the bottom of the pan. Bring the mixture to a gentle simmer.

Add the cooked penne, baby spinach, and crushed red pepper flakes. Fold gently until the spinach just wilts and the sauce coats the pasta.

Stir in the grated Parmesan until it melts and makes the sauce glossy. Taste and adjust seasoning. Serve immediately with extra Parmesan if desired.