Bring a large pot of salted water to a boil. Add pasta and cook until al dente, about 8-10 minutes. Drain and return to pot with a drizzle of olive oil.

Heat 2 tbsp olive oil in a large skillet over medium heat. Sauté chopped onion for about 2 minutes until translucent.

Stir in fennel seeds and sauté for another 2 minutes.

Add spinach and minced garlic to the skillet, cooking for about 2 minutes until spinach wilts.

Pour in stewed tomatoes and add sliced Italian sausage. Simmer for 5 minutes until cooked through.

Mix in the cooked pasta with the sauce. Season with salt and pepper to taste.

Serve immediately, garnished with extra olive oil or Parmesan if desired.