2tspkosher salt(use less or more according to your liking)
¾tspblack pepper(use less or more according to your liking)
½cup a combination of cheddar and gruyere cheese(or gruyere cheese only)
2tbspgrated parmesan cheese
1½cupspanko bread crumbs
Preheat the oven to 350°F.
Cook the Onion and Squash in a skillet:
Melt 2 tablespoons of butter and 1 tablespoon of oil in a large, ovenproof skillet over medium-high heat.
Add the onion and thyme and cook, stirring, until the onion softens, about 5 minutes.
Stir in the squash, garlic powder, ground nutmeg, ground sage, salt, and black pepper, cover and cook for 10 minutes, stirring occasionally.
Bake the Squash gratin in the Oven:
Spoon the squash mixture into the prepared baking dish or use an ovenproof skillet.
Pour the heavy cream over the mixture evenly.
In a medium bowl, combine the bread crumbs and 2 Tbs. olive oil and mix in the Gruyère and cheddar cheese. Sprinkle evenly over the squash. Bake for 35 to 40 minutes, or until the top is browned and the squash is very tender.