Bring a large pot of generously salted water to a rolling boil over high heat. Add the pappardelle pasta, stirring gently to prevent sticking. Cook according to package instructions until al dente, usually about 8-10 minutes.

In a large sauté pan, heat 2 tablespoons of olive oil over medium-high heat. Once shimmering, add the Italian sausage, breaking it apart with a wooden spoon. Cook for 5-7 minutes or until browned and cooked through, then transfer to a plate, leaving drippings in the pan.

Lower the heat to medium and add another tablespoon of butter to the same pan. Once melted, add the chopped onion and thinly sliced fennel. Sauté for about 8 minutes or until golden and caramelized.

Add the minced garlic to the pan and cook for an additional 1-2 minutes or until fragrant. Stir in 2 tablespoons of tomato paste and 1 tablespoon of Calabrian chili paste, mixing well.

Pour in a splash of dry white wine, scraping the bottom of the pan to release caramelized bits. Increase the heat slightly and let it simmer for about 2 minutes.

Stir in a cup of tomato purée, followed by ½ cup of heavy cream and the cooked sausage. Allow to simmer on low heat for about 5 minutes until heated through and slightly thickened.

Once the pasta is al dente, reserve a cup of pasta water, then drain the rest. Add the cooked pappardelle to the sauce and toss gently to coat. Add reserved pasta water if needed for consistency.

Remove the pan from heat and stir in freshly grated Parmesan cheese, melting and blending into the dish. Season with salt and black pepper to taste.