Begin by heating the olive oil in a large pot over medium heat. Once the oil is shimmering, add the Italian sausage. Use a wooden spoon to break it up as it cooks until browned and fully cooked, about 5-7 minutes.

Add the diced onion and minced garlic to the pot with the cooked sausage. Sauté until the onion becomes translucent, about 3 minutes.

Pour in the chicken broth, bringing everything to a gentle boil. Add the butternut squash cubes along with thyme, sage, and crushed red pepper flakes. Reduce heat to a simmer and cook for about 15-20 minutes until the squash is tender.

Blend the soup until smooth using an immersion blender or by transferring it to a standard blender in batches.

Stir in the heavy cream and cheese tortellini. Bring back to a gentle simmer and cook for an additional 5-7 minutes until the tortellini are tender.

Taste the soup and season with salt and pepper as needed.

Ladle the soup into bowls and garnish with fresh parsley if desired.