Preheat the oven to 180 degrees Celsius or 350 degrees Fahrenheit.
Cut the bloomer lengthways through the middle and remove the top. Hollow out the base of the loaf to make a shell then brush the inside with olive oil.
Bake for 10 minutes until crisp then leave to cool. Turn the oven down to 120 degrees Celsius or 250 degrees Fahrenheit. Melt the butter and sugar in a large, non-stick frying pan with a little oil and add the shallots, cut side down.
Fry for 5 minutes until golden then turn and fry for a further 2 to 3 minutes. Transfer to the oven for 15 minutes until soft.
Spoon the shallots into the bread shell then scatter the sliced hot dogs over the top. Whisk the eggs, egg yolks, cream, milk and mustard together until smooth then stir through the chives and half of the cheese.
Season with plenty of salt and pepper then pour over the hot dogs and shallots. Sprinkle over the remaining cheese then bake for 35 to 40 minutes until just set, but with a slight wobble in the centre.
Remove from the oven and leave to cool before slicing.