How to Make Croque Monsieur

• 5 tbsp plus 8 tbsp unsalted butter, divided
• 1/4 cup all-purpose flour
• 4 cups whole milk
• 2 egg yolks
• 2 tsp kosher salt
• 1/2 tsp ground nutmeg
• 8 ½-inch-thick slices pain de mie or other white bread
• 8 slices ham, such as French jambon
• 8 slices Gruyère cheese

1. 1

   Make the béchamel sauce: In a medium saucepot over medium heat, warm 5 tablespoons butter until melted. Gradually add flour and stir with a wooden spoon until smooth.

2. 2

   Cook the mixture for 2-3 minutes, keeping a close eye on it to avoid unwanted burning. In a separate saucepot, heat the milk until it is just about to boil.

3. 3

   Add the hot milk to the butter mixture, ½ cup at a time, constantly whisking. Cook 12 minutes, stirring constantly. Turn heat off.

4. 4

   Slowly stir in 1 egg yolk at a time. Season with salt and nutmeg. Heat oven to 300°F.

5. 5

   Assemble the sandwich: Generously spread four slices of bread with béchamel sauce. Top each with ham and cheese and cover with remaining bread.

6. 6

   Melt the remaining 8 tablespoons butter and brush both sides of sandwiches with melted butter. Fry sandwiches in a hot cast iron pan or on a griddle until golden brown. Top sandwiches with more béchamel sauce and transfer to the oven to continue cooking until cheese bubbles, about 5-10 minutes.

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