Butternut Squash Gratin with Mushrooms, Caramelized Onions and Gruyere

1. Preheat oven to 425ºF. Add chopped squash to a bowl and toss with 1 tablespoon olive oil, salt and pepper. In a single layer, place squash on baking sheet or large cast iron pan (what I used) and roast until soft, about 30 minutes.

2. While squash is roasting, heat the remaining 1 tablespoon olive oil in a pan over medium-high heat. Add sliced onions and cook for 10 minutes. Add brown sugar, balsamic vinegar, salt and pepper. Reduce heat and continue to cook 15-20 minutes. Remove from heat.

3. When squash is done roasting, remove from the oven and top with caramelized onions, sliced mushrooms, and Gruyere. Reduce oven temperature to 400ºF and cook 15-20 minutes or until the cheese has melted and started to brown. Serve sprinkled with fresh basil.