Preheat the oven to 350°F.
Add the cubed butternut squash, sweet potato, and onion to a large baking dish or sheet pan. Drizzle with the olive oil and season generously with salt and pepper. Toss until evenly coated.
Slice the top off the head of garlic to expose the cloves. Drizzle with a little olive oil, wrap in foil, and place on the pan with the vegetables.
Roast for about 45 min to an hour, or until the butternut squash and sweet potato are very tender and the vegetables are lightly caramelized.
Remove from the oven and carefully squeeze the roasted garlic cloves from the skin.
Add the roasted butternut squash, sweet potato, onion, and garlic to a high-powered blender along with 4 cups of the chicken stock, cottage cheese, sage, thyme, and sugar. Blend until completely smooth and creamy. Depending on your blender size, you may need to work in batches.
Pour the blended soup into a large pot or Dutch oven. Stir in the remaining 1 cup chicken stock and bring to a gentle simmer over medium heat.
Add the ravioli directly to the soup and cook according to the package directions, usually about 4-6 minutes for refrigerated ravioli. Stir gently and occasionally to prevent the ravioli from sticking to the bottom or tearing.
Once the ravioli are tender, reduce the heat to low. Stir in the Parmesan cheese and heavy cream until the cheese has melted and the soup is creamy and warmed through. Avoid bringing the soup to a boil once the cream has been added.
Taste and season with additional salt and pepper as needed. If the soup is thicker than you’d like, add an extra splash of chicken stock until it reaches your desired consistency.
Ladle into bowls and finish with freshly grated Parmesan, red pepper flakes, and plenty of freshly cracked black pepper. Serve warm and enjoy!