Ingredients

The following ingredients have 4 Servings
  • 2 red onions
  • olive oil for brushing
  • 2 Tbsp unsalted butter (divided)
  • 1 Tbsp all purpose flour
  • 2/3 cups heavy cream
  • 3 Tbsp dry sherry
  • salt and fresh cracked black pepper
  • dash of nutmeg (I grate mine fresh)
  • handful of fresh thyme
  • 1 cup shredded Gruyere cheese
  • 1/2 cup fresh breadcrumbs

Instruction

  • Set oven to 400F
  • Peel and thickly slice the onions.
  • Heat a grill pan until quite hot, and brush the onion slices lightly with olive oil. Grill the slices for a minute or two on each side so that they get slightly softened and have nice grill marks. Set them aside.
  • In a saucepan, heat 1 Tbsp of the butter over medium heat, and stir in the flour. Cook for a minute, stirring constantly. Pour in the cream and sherry and whisk until smooth. Stir constantly while the mixture comes up to a simmer and is thickened. Add salt and pepper to taste and the dash of nutmeg.
  • Pour the sauce into a cast iron skillet or gratin dish. Arrange the onion slices over the sauce.
  • Sprinkle the cheese evenly over all.
  • Stir the breadcrumbs together with the last tablespoon of melted butter, and a little salt, pepper, and a few thyme leaves. Sprinkle the breadcrumbs over the cheese,
  • Bake for about 20 minutes until browned and bubbling. You can run the gratin under the broiler at the last minute if you want extra browning,