01 - Bring a large pot of salted water to a boil. Cook pasta according to package directions until al dente. Reserve ½ cup pasta water before draining. Set aside.
02 - Heat olive oil in a large skillet over medium-high heat. Add ground beef and cook, breaking apart with a spoon, until browned and cooked through, about 5–6 minutes. Drain excess fat if needed.
03 - Add diced onion to the skillet and sauté for 2–3 minutes until translucent. Stir in garlic and cook for 30 seconds until fragrant.
04 - Mix in chopped sun-dried tomatoes and cook for another minute to incorporate flavors.
05 - Pour in beef or chicken broth and bring to a simmer. Let liquid reduce by half, approximately 3 minutes.
06 - Reduce heat to medium-low. Add heavy cream, parmesan cheese, Italian herbs, and red pepper flakes. Stir continuously until cheese melts and sauce becomes smooth and creamy, about 2–3 minutes.
07 - Add cooked pasta and baby spinach if using to the skillet. Toss thoroughly to coat, adding reserved pasta water as needed for desired consistency. Season with salt and pepper to taste. Serve hot with additional parmesan and fresh basil if desired.