Roughly cut the bread into 2 inch cubes. Put half of these into a greased 9x9" square pan (you can use any pan that will fit all the bread).
Sprinkle over the sliced ham and half the cheese. Top with the remaining bread.
In a small bowl, or glass measuring jug, whisk together the eggs, cream, mustard, and some salt and pepper.
Pour this mixture over the bread. Top with remaining cheese. Cover with foil and place in the refrigerator for 20 minutes.
Preheat the oven to 365℉/185℃.
Place the dish into the oven, bake for 15 minutes, then remove the foil and let bake for a further 15 minutes, until the top looks golden. Remove and serve while still warm!