Thomas Keller’s Croque Madame

Name: Thomas Keller’s Croque Madame
Prep time: 15 min
Cook time: 60 min
Total time: 75 min
Yield: 4 sandwiches (or 2, depending on whether you double stack)
Ingredients: 8 slices brioche bread; 30g (1 oz) unsalted butter, softened; 8 thin slices cooked ham; 8 slices Swiss cheese; vegetable oil, for frying; 4 large eggs; finely chopped chives, to serve; Mornay sauce; 45g (1.5 oz) unsalted butter; ½ cup diced onion; sea salt; 25g (0.8 oz) plain (all-purpose) flour; 2 cups cold milk; 1 cup double (heavy) cream, or as needed; 1 bay leaf; 3 black peppercorns; 3 whole cloves; pinch of freshly grated nutmeg; pinch of ground white pepper, plus extra for seasoning; 35g (1 oz) grated Comte or Emmental cheese