Add <quantity>50<unit>g</unit></quantity> of unsalted butter to a pot over low heat and melt until foamy

Add <quantity>50<unit>g</unit></quantity> of all-purpose flour

Whisk until combined

Add <quantity>400<unit>ml</unit></quantity> of whole milk and whisk until combined

Grate some nutmeg to taste

Season with ground black pepper to taste

Add a pinch of salt to taste

Mix well and simmer on low heat until it thickens

Remove from heat and strain it into another saucepan

Put the sauce back on low heat, and add <quantity>100<unit>g</unit></quantity> of grated gruyère cheese

Whisk to incorporate the cheese

Crack <quantity>2</quantity> eggs on a bowl, and separate the yolks from the whites

Remove sauce from heat. Add in the egg yolks while whisking until combined

Put the sauce back on low heat. Continue to whisk until achieving a creamy consistency

When it coates the back of a spoon, the Mornay Sauce is ready

Pre-heat the oven to <temperature>225<unit></unit>ºC</temperature>

Crack <quantity>6</quantity> egg into a bowl

Add <quantity>600<unit>ml</unit></quantity> of heavy cream

Season with black pepper to taste

Add a pinch of salt

Whisk the mixture to incorporate all ingredients

Dip <quantity>6</quantity> slices of brioche into the mixture

Add <quantity>3</quantity> slices of ham on top of each brioche

Add <quantity>3<unit>tbsp</unit></quantity> of grated Gruyère cheese on top of each

Drizzle <quantity>3<unit>tbsp</unit></quantity> of the mixture on the top of each slice

Dip the remaining <quantity>6</quantity> slices of brioche into the mixture

Cover the sandwiches with the dipped brioche slices

Add <quantity>3<unit>tbsp</unit></quantity> of grated Gruyère cheese on top of the sandwiches

Drizzle <quantity>1<unit>tbsp</unit></quantity> of the mixture

Bake in the oven at <temperature>225<unit>ºC</unit></temperature> until the cheese has melted and is golden brown

When the cheese is melted and golden brown, remove from the oven

Melt <quantity>½<unit>tbsp</unit></quantity> of butter over high heat

Add a pinch of salt

Add some black pepper to taste

Crack <quantity>1</quantity> egg into the frying pan once the butter has melted

Gently shake the frying pan to ensure the egg isn't stuck to the pan. The egg will be properly cooked when the egg white firms up and starts to lightly color on the edges. When the egg is ready remove from the pan

Plate each sandwich and pour <quantity>1<unit>ladle</unit></quantity> of warm Mornay sauce on top of it

Add <quantity>1</quantity> fried egg on top of each Croque Madame

Garnish each Croque Madame with finely chopped chives to taste

Enjoy!