Croque Madame Casserole

Instructions

1. Prepare the béchamel sauce
   In a medium saucepan over medium heat, melt 4 tablespoons of butter. Add flour and whisk continuously for 2 minutes until smooth and bubbling. Gradually whisk in the warm milk. Continue cooking, whisking constantly, until the sauce thickens, about 5-7 minutes. Remove from heat and stir in nutmeg, Dijon mustard, and 1 cup of grated Gruyère. Season with salt and pepper to taste.
2. Assemble the base layer
   Preheat oven to 375°F (190°C). Butter a 9x13-inch baking dish. Arrange 6 slices of bread in a single layer in the baking dish. Spread each slice with some béchamel sauce, then top with ham slices, dividing evenly. Sprinkle with 1/2 cup of the remaining Gruyère.
3. Complete the casserole assembly
   Top with the remaining 6 slices of bread. In a large bowl, whisk together the eggs, heavy cream, salt, and pepper. Pour this mixture evenly over the bread. Let stand for 10 minutes to allow the bread to absorb some of the egg mixture. Spread the remaining béchamel sauce over the top layer and sprinkle with the last 1/2 cup of Gruyère.
4. Make egg depressions
   Using the back of a large spoon, make 6 evenly spaced depressions on the top of the casserole. Crack an egg into each depression. Dot the remaining butter around the top of the casserole, avoiding the eggs.
5. Bake the casserole
   Bake in the preheated oven for 35-40 minutes, or until the eggs are set to your liking and the casserole is golden brown and bubbling. If the top is browning too quickly, cover loosely with aluminum foil.
6. Serve
   Let the casserole stand for 5 minutes before serving. Garnish with chopped chives. Serve warm, ensuring each portion includes an egg on top.