In a large skillet or saucepan, heat the olive oil over medium heat. Add the diced onion and sauté until translucent, about 5 minutes.

Add the minced garlic, diced carrot, and diced celery to the skillet. Cook for an additional 5 minutes until the vegetables are softened.

Remove the sausage from its casings and add it to the skillet. Break it up with a wooden spoon and cook until browned, about 6-8 minutes.

Stir in the crushed tomatoes, tomato paste, oregano, basil, salt, and pepper. Pour in the broth and bring the mixture to a simmer. Reduce the heat to low and let it cook for about 20-30 minutes, stirring occasionally.

While the sauce is simmering, bring a large pot of salted water to a boil. Add the pappardelle pasta and cook according to package instructions until al dente. Drain the pasta, reserving a cup of pasta water.

Toss the cooked pappardelle with the sausage ragu, adding reserved pasta water as needed to achieve desired consistency.

Serve the ragu over the pasta, topped with grated Parmesan cheese and fresh basil leaves.