Melt the butter in a small pan. In a bowl set over pan of simmering water, or in a food processor, mix the egg yolks, lemon juice and mustard.
Gradually spoon in tiny drops of the warm melted butter (leave the white solids behind in the pan), whisking (or pulsing if using a food processor) all the time. Season and loosen the mixture with a little more lemon juice if needed. Keep warm.
Melt a knob of butter in a frying pan over a medium heat, add the sugar and allow to dissolve. Add the ham, sprinkle over the cayenne and fry for 4 minutes or until glazed, turning every now and then.
Put enough water to come up to 5 cm into a large pan and bring to the boil over high heat. Reduce the heat down to a shudder.
In turn, crack each egg into a teacup and carefully slide it into the water, on separate sides of the pan. Cook for 3 minutes until the white has set. Remove using a slotted spoon and briefly drain on kitchen paper.
Top the toasts with the glazed ham, poached eggs and then spoon the warm hollandaise over the top. Finish with some cracked black pepper and the pumpkin seeds.