Instructions

1. Preheat oven to 375 F.
2. Dress squash with olive oil, and season generously with salt and pepper.
3. Arrange in single layer on 2 baking trays lined with parchment. Roast for 20 minutes or until soft.
4. Meanwhile, warm milk in saucepan over medium low heat, just until bubbles appear at edges. Rub or twist sage leaves gently until fragrant, and add to warm milk. Remove from heat and let steep for about 20 minutes.
5. Melt butter in large, heavy-bottomed saucepan. Sauté shallots until soft and translucent, about 5 minutes. 
6. Pull sage leaves from milk, squeezing to remove any extra liquid in leaves. 
7. Combine cheeses in large bowl, and toss to mix. 
8. Add gluten-free baking mix to sautéed shallots. Whisk vigorously to incorporate. 
9. Slowly dribble sage-infused milk into shallots while stirring over low heat. Mixture will alternate between lumpy and smooth as milk is incorporated but should end up smooth and creamy.
10. Add 3 cups cheese blend a little at a time, stirring as cheese melts.
11. Add mustard to cheese sauce.
12. Add salt and pepper to taste.
13. Coat squash with cheese sauce.
14. Pour into 9-by-13-inch baking dish.
15. Top with remaining cup of cheese blend and bake at 375 F for 40 minutes. If desired, top with fried onions 10 minutes before done. 
16. Allow to rest and cool for at least 15 minutes before serving.