Butter the bread on both sides and place in a small frying pan (preferably one that can go under the grill as well as on the hob). Cook until golden on one side, then flip the bread over and cook the other side.
Drizzle the chicken stock over the bread to soften it.
Mix the ham and cheese together and put this mixture on top of the bread. Make a little nest in the middle of the topping and then break the egg into it.
Put this under the grill until the egg is cooked to your liking and the cheese around the sides is golden and melting. How long this takes depends on your grill – domestic ones really vary – so keep an eye on it. In my grill it takes seven minutes.