From: Chef Jamie Bissonnette, KO Prime, Boston, MA. Yield: 4 servings.
2 Tbsp. unsalted butter
1 large shallot, minced (about 2 Tbsp.)
½ tsp. garlic, minced
2 Tbsp. flour
1 tsp. salt, divided
½ tsp. black pepper, freshly ground
⅛ tsp. ground nutmeg
1 cup whole milk
1½ cups (6 oz.) Wisconsin Gruyère cheese, shredded, divided
8 cups water
1 tsp. distilled white vinegar
8 large eggs
4 slices brioche or other eggy bread
4 slices prosciutto, Serrano or Ibérico ham
chopped chives, optional
white truffle oil, optional
For Béchamel sauce: Melt butter in heavy medium pan. Add shallots and garlic and sauté, stirring, until soft and fragrant. Add flour, stirring constantly for about 2 minutes (do not scorch). Add ½ teaspoon salt, pepper and nutmeg. Gradually stir in milk. Continue cooking and stirring until the sauce boils and thickens. Remove from heat and add 1 cup Gruyère cheese, stirring until melted. Set aside and keep warm.
For egg gratin: Preheat oven to 400°F. Pour water into large, shallow pan or skillet. Add remaining ½ teaspoon salt and white vinegar. Bring to boil and then lower heat to simmer. Carefully crack eggs into water, keeping it simmering. Poach until soft set, about 3 minutes. Remove eggs with a slotted spoon; drain well. While the eggs are poaching, toast the brioche and place one ham slice in each of 4 individual serving dishes. Place 2 eggs on each ham slice. Spoon ¼ of the sauce over each serving. Bake for 5 minutes. Sprinkle remaining cheese over eggs and garnish with chopped chives, if desired. For a decadent finish, drizzle white truffle oil over each serving.