Preheat the oven to 350°F. Butter a 13x9x2 inch glass baking dish.
Melt the butter in large skillet over medium- high heat. Add the onions; sauté until the onions are lightly browned, about 8 minutes (be sure to tend to them and stir every couple of minutes to prevent burning). Add the butternut squash; sauté 4 minutes. Sprinkle the sugar, salt and pepper over the vegetables; sauté until the onions and squash begin to caramelize, about 5 minutes.
Spread the vegetable mixture in the prepared dish. Pour the broth over. Cover tightly with foil and bake 45 minutes. (Squash mixture can be made 1 day ahead. Cool, then cover and refrigerate. Reheat in 350°F. oven until heated through, about 10 minutes).
Increase the oven temp. to 400°F. In a medium bowl, combine the Panko, cheese, rosemary and thyme. Sprinkle over the gratin. Bake uncovered until top is golden brown and crisp, about 30 minutes.
Notes
If you can purchase pre-cut butternut squash (available at Trader Joes, Costco and some regular markets), it makes this recipe much easier. Don't use frozen squash.
To prepare this recipe GLUTEN FREE, use GF Panko breadcrumbs, and make sure the brand of broth you use is known to be GF.
To prepare this recipe as vegetarian, use vegetable broth.
If you are counting WW Points, be sure to use reduced fat cheddar cheese.