1. In a large pot, bring salted water to a boil. Add the penne pasta and cook until al dente, about 10-12 minutes. Drain and set aside.
2. In a large skillet, heat the olive oil over medium heat. Add the chopped onion and sauté until translucent, about 3-4 minutes.
3. Add the minced garlic and cook for an additional minute, ensuring it doesn’t brown.
4. Add the sausage to the skillet, breaking it into smaller pieces with a spoon. Cook until browned and cooked through, about 8-10 minutes.
5. Stir in the fennel seeds, red pepper flakes, salt, and pepper. Cook for another minute to release the spices’ aroma.
6. Pour in the chicken broth, scraping up any browned bits from the bottom of the skillet. Let it simmer for 2 minutes.
7. Reduce the heat to low and stir in the heavy cream. Allow it to simmer gently until the sauce thickens slightly, about 5 minutes.
8. Add the cooked pasta to the skillet, tossing it in the sauce until well coated.
9. Sprinkle the Parmesan cheese over the pasta and stir until melted and creamy.
10. Garnish with fresh basil leaves before serving.

The secret to this dish, as Mama Lou would say, is patience and love. Let the flavors meld together and take your time to enjoy the process.