I LOVE French onion soup. If I see it on a menu, I order it -and I critique the hell out of it. The broth needs to be flavorful and well-seasoned, the onions tender, the bread al dente, and the cheese PLENTIFUL, with crispy bits, of course!
This version simplifies the process a bit, and packs a punch of flavor. You can make the caramelized onions in advance and refrigerate them until you're ready to cook them. Just heat the onions in the casserole pan at 350 degrees until hot, then add the croutons, cheese and broil.
FRENCH ONION CASSEROLE
5 large yellow onions, julienned
1 stick unsalted butter
1/4 cup extra virgin olive oil
Kosher salt and freshly ground black pepper
1/4 cup white wine
2 tablespoon all-purpose flour
3/4 cup beef broth
3 sprigs of thyme, leaves removed
2 cups garlic croutons
8 ounces sliced swiss cheese
In a large, high-sided skillet, melt the butter over medium heat. Add the olive oil and onions. Cook, stirring often, over medium heat until the onions are amber colored, about 30 minutes. Season with salt and pepper, to taste. Sprinkle the flour over the onions and stir until it has been absorbed. Add the white wine, and, with a wooden spoon, scrape any brown bits from the pan. Cook until the wine reduces, about 2 minutes. Add the beef broth and thyme. Cook until the sauce thickens. Add salt and pepper, to taste.
Preheat the broiler. Transfer the onions to a 8"x12" casserole dish and level them out with the back of a spoon. Sprinkle the croutons evenly over the onions and layer the cheese over the croutons, covering the entire top. Broil until the cheese melts and starts to crisp, about 3 minutes. Serve immediately.