Prepare the pappardelle noodles according to instructions on package; then, drain the noodles very well, and keep them warm while you prepare the sauce.
Place a large, heavy-bottom pan or braising pot over medium-high heat, and add about 2 tablespoons of olive oil; once the oil is hot, crumble the spicy Italian sausage into the pan in small chunks, allowing it to brown.
Once browned, remove the sausage from the pan with a slotted spoon and place into a small bowl.
Add the sliced onion into the pan with the sausage drippings, and caramelize for roughly 5 minutes, stirring to prevent burning; add salt, Italian seasoning, and cracked black pepper.
Add the sliced bell peppers; sauté for about 2 minutes until slightly tender and golden; then, add garlic and after it becomes aromatic, add white wine and reduce.
Add in the diced tomatoes with their juice and return the browned sausage, gently folding to combine; simmer for about 3 to 4 minutes.
Drizzle in 2-3 tablespoons of olive oil to the sauce, stir in chopped parsley and half of the julienned basil.
Add the cooked pappardelle noodles directly into the sauce, gently toss and combine.
To serve, add equal portions to bowls, garnishing with remaining basil and optionally shaved parmesan and an extra drizzle of olive oil.