1. Bring a large pot of salted water to boil and cook pappardelle until al dente. Reserve 1 cup of pasta water and drain.

2. In a large skillet, heat olive oil over medium-high heat. Add sausage and cook until browned and slightly crispy, breaking it into small pieces.

3. Add the sliced fennel to the skillet with the sausage. Sauté until softened and golden, about 6-8 minutes.

4. Stir in the Calabrian chili paste and cook for 30 seconds to bloom the flavors.

5. Reduce heat to medium-low. Pour in the heavy cream and stir to combine. Let the sauce simmer for 4-5 minutes until slightly thickened.

6. Add the cooked pasta and a splash of pasta water to the sauce. Toss to coat the noodles and let it cook together for 1 minute.

7. Stir in Parmigiano Reggiano, lemon zest, and lemon juice. Season with salt and black pepper to taste.

8. Simmer for another minute until the sauce clings beautifully to the pasta.

9. Serve immediately with extra cheese on top if desired.