To make Morne sauce, melt butter in a small non-stick saucepan on low heat until it just starts to bubble. Add the flour and cook, stirring for about 2 minutes or till smooth.
Slowly add milk, whisk
continuously, and cook till thick. Remove from heat. Add salt, pepper powder, nutmeg powder and Dijon mustard. Add some grated Gruyere cheese and Parmesan cheese, mix and set aside.
Arrange the bread
slices on a baking tray and toast them in the preheated oven for a few minutes each side or till lightly toasted.
Spread Morne sauce
over the toasted slices. Arrange the ham slices and sliced cheese on them.
Place the tray in the
preheated oven and bake for 5 minutes or till the cheese is bubbly and lightly browned.