To make the filling, heat oil in a nonstick skillet on medium heat, then add onions. Sauté until onions start to brown. Once the onions begin to caramelize, add garlic and sauté for 1 minute, or until fragrant. Turn heat back up to medium and add turkey, salt, pepper, dried herbs, fennel, paprika, chilli flakes , and sugar. Sauté mixture until turkey/chicken is just cooked through, about 7-8 minutes. Transfer to a large mixing bowl and allow to cool slightly. Stir in the parmesan cheese.