4. Prepare Filling
While the squash cooks, make the filling. Heat the oil in a large skillet over medium heat. When the oil is shimmering, add the sausage, onion, and garlic, and cook until the sausage is no longer pink and the onion is tender. Transfer to a large bowl.
Add the quinoa, pepitas, and cherries to the sausage mixture and stir well to combine. Season to taste with salt and pepper.