Roasted Parmesan Creamed Onions


3 sweet onions, peeled and thinly sliced
1 cup heavy cream
1/4 cup white wine
1/2 cup parmesan cheese, grated

4 tablespoons unsalted butter
3 tablespoons extra-virgin olive oil

1 teaspoon garlic powder
1/4 teaspoon cayenne, optional
Kosher salt and freshly ground pepper, to taste