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

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

Stir in the minced garlic and cook for 1 minute until fragrant.

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

Pour the chicken broth and half-and-half into the skillet. Stir 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 wilts and everything is evenly coated.

Stir in the grated Parmesan cheese until it melts and the sauce clings to the pasta. Taste and adjust seasoning if needed. Serve immediately.