Pre-heat the oven to 180°C/350°F/Gas Mark 4.
To make the béchamel sauce warm the milk and cream in a saucepan.
Heat Whirl Butter Alternative in a pan stir in the flour and make a roux. Keep stirring for 2-3 minutes over a medium heat, but do not brown.
Slowly add the milk mix to the roux stirring each addition well before adding the next until it has all been added. Keep stirring to a thicken. Add the onion powder, garlic powder and a pinch of nutmeg, then season with salt and white pepper to taste. Set to one side.
Take the 4 slices of bread, brush one side with Whirl butter Alternative and place the bread buttered side up under the grill to toast.
Remove from the grill and spread the untoasted side with a little Lion Dijon Mustard, then spread some of the béchamel sauce over the top. Add 1 slice of cheese and a slice of ham.
Sandwich two of the slices together and spread a little more béchamel over the top slice. Finish with the last slice of cheese, then place in a hot oven for 10-15 minutes until the cheese has melted and turned golden brown.