Step 1

Melt the butter in a small saucepan over medium heat.

Step 2

Add flour and stir it around, letting it cook for 1-2 minutes.

Step 3

Whisk in the milk and stir continually, scraping along the inside rim to ensure there's no scorching.

Step 4

As the sauce heats up, season it with salt, white pepper and nutmeg.

Step 5

Remove from heat once thickened.

Step 6

Make the béchamel.

Step 7

Set the oven to broil on high.

Step 8

Spread butter and mustard on the bottom slice.

Step 9

Add a layer of ham.

Step 10

Paint on a thin strip of béchamel over the ham.

Step 11

Sprinkle a bit of cheese over the béchamel to help the top slice stick.

Step 12

Cover up the sandwiches and spoon on béchamel over the top slice.

Step 13

Add a handful of cheese on top of the béchamel.

Step 14

Pop into the oven for a quick broil. Check frequently to make sure it doesn't burn!