2 medium yellow onions, cored and quartered lengthwise
¼ cup olive oil
Kosher salt and freshly ground black pepper, to taste
2 tbsp. unsalted butter
2 tbsp. flour
1 cup heavy cream
¼ cup dry white wine
Freshly grated nutmeg, to taste
½ cup finely grated parmesan
3 oz. Gorgonzola, crumbled
¼ tsp. paprika
1. Heat oven to 350°. Toss onions with oil in a 9″ × 11″ baking dish and season with salt and pepper. Bake, stirring occasionally, until soft and lightly browned, about 1 hour; set aside. Heat oven to broil.
2. Heat butter in a 2-qt. saucepan over medium-high heat; add flour, and cook, stirring, until smooth, about 1 minute. Add cream and wine, and cook, stirring, until thickened, about 5 minutes. Season sauce with salt, pepper, and nutmeg.
3. Pour sauce evenly over onions. Sprinkle with parmesan, dot with Gorgonzola, and sprinkle with paprika; broil until cheese is melted and golden brown on top, about 2 minutes.