Preheat your oven to 200°C (390°F).
Prepare the béchamel sauce: In a saucepan over medium heat, melt the butter. Add the flour and whisk constantly for 1-2 minutes until a smooth paste (roux) forms.
Gradually whisk in the warmed milk, a little at a time, ensuring no lumps form. Continue whisking until the sauce thickens and coats the back of a spoon. This should take about 5-7 minutes.
Season the béchamel with salt, black pepper, and a pinch of nutmeg. Remove from heat.
Lightly toast the bread slices in a toaster or pan for a minute or two until slightly golden. This helps prevent sogginess.
Lay 4 slices of toasted bread on a baking sheet. Spread a thin layer of Dijon mustard on each slice, if using.
Divide half of the grated Emmental cheese among these 4 slices.
Arrange the prosciutto slices evenly over the cheese.
Top with the remaining 4 slices of bread, pressing down gently.
Generously spread the béchamel sauce over the top of each sandwich, ensuring good coverage.
Sprinkle the remaining grated Emmental cheese evenly over the béchamel sauce.
Bake in the preheated oven for 10-15 minutes, or until the cheese is melted, bubbly, and golden brown, and the edges of the bread are crispy.
Serve immediately and enjoy your royal treat!
- 🧈 For an extra rich flavor, brown the butter slightly before adding the flour for the béchamel.
- 🔪 A serrated knife works best for slicing through the crispy exterior of the sandwich without squishing it.
- 🌿 Garnish with a sprinkle of fresh chives or parsley for a pop of color and freshness.
- ❄️ Assemble the sandwiches ahead of time and refrigerate. Add the top béchamel and cheese just before baking.
- 🧀 Don't be shy with the Emmental; the more cheese, the better the melt and flavor!
