Set a large pot over medium-high heat. Once hot, drizzle in the oil and add the chicken sausage and break it up with a wooden spoon. Season with fennel seeds, Italian seasoning, and crushed red pepper flakes. Cook until the sausage has begun to crisp and is fully cooked through. Transfer to a plate and set aside.

Add the onion, carrots, celery, red bell pepper, and garlic. Cook, stirring often, until the veggies have softened, about 5 to 8 minutes. Stir in the tomato paste and chili pepper paste (if using) and cook for about 30 seconds or so. Add the tomato purée and chicken stock and bring up to a simmer. Season with a large pinch of salt and pepper.

Carefully blend with an immersion blender until smooth. Or carefully transfer to a blender and blend. Give it a taste and adjust seasoning accordingly. Bring back up to a simmer and then add in the kale, cooked sausage and the tortellini that has been cooked according to package directions. You don't want to cook the tortellini in the soup as it'll absorb too much moisture. Cook it in a pot of boiling water and then transfer to the soup.

Stir until the kale has wilted slightly. Serve with some parmesan on top, a drizzle of oil and some crusty bread for dipping. Enjoy!