Heat a 5 to 6-quart pot over medium-high heat. Add in 1 pound ground Italian sausage. Use a large spoon to break it up, and cook until browned, about 5 minutes. Drain any excess grease.
Meanwhile, dice 1 large yellow onion and finely dice 4 medium carrots and 4 medium celery ribs into similarly sized pieces as the onion. Add to the pot with the sausage and cook until vegetables are softened and sausage is cooked through, about 7 to 10 minutes more, stirring frequently. Add 5 teaspoons minced garlic during the last 1 to 2 minutes of cooking.
Pour in 4 cups beef broth and 1 (30 ounce can) fire roasted diced tomatoes. Drain and rinse the 1 (15 ounce can) red kidney beans and 1 (15 ounce can) cannellini beans to remove the extra starch, then add them to the pot. Season with 1 teaspoon salt, 1/2 teaspoon black pepper, and 1/2 teaspoon dried thyme. Bring to a boil over high heat.
Add 1 1/2 cups ditalini pasta. Reduce heat to medium and simmer until pasta is al dente, about 7 minutes.
Serve hot and garnish generously with 1/4 cup chopped fresh basil, 1/2 cup freshly grated parmesan cheese, and additional salt and pepper to taste.
Notes
Instead of 1 pound of Italian sausage, you can use lean ground beef, ground turkey, or even diced ham.
Add some greens with 2 cups of roughly chopped kale added in with the ditalini to simmer, or 2 cups of baby spinach once the soup has finished cooking.