In a bowl, whisk together the egg, mustard, sugar, salt and half the breadcrumbs.
Once combines, spread the paste all over the top of the ham. Once you have an even layer on top, add the rest of the breadcrumbs evenly across the topping.
Pop the ham under the grill for about 15 minutes - but watch carefully so that the topping cooks, but does not burn.
Swedish ham is served cold or just a bit warm, so no need to worry too much about heating up the whole ham.
Serve whole on the Julbord Christmas table - and slice as needed. Serve with a good sweet coarse mustard with bite - and of course Smorgasgurka pickles.