Ingredients
Heat a large Dutch oven over medium heat. When the pot is hot, add the sausage and onion. Cook, breaking up the sausage with a spoon, until some fat has rendered and the meat has browned all over, about 8 minutes. Add the garlic, tomato paste, thyme, Italian seasoning, salt, and pepper. Cook, stirring, until fragrant and the tomato paste is dark brick red, 1 to 2 minutes more.
Add the carrots and celery. Cook, stirring, until they begin to soften, about 5 minutes. Pour in the broth. Bring to a simmer and cook until the vegetables are tender and the flavors melded, 10 to 15 minutes.
Stir in the kale, milk, and pesto and cook until the kale is slightly wilted, about 2 minutes. Add the tortellini and Parmesan and cook until the tortellini is cooked and the cheese is melted, 3 minutes more.
To serve, ladle the soup into bowls and top with more Parmesan and fresh basil.