Generously butter an ovenproof dish, approx. 30cm x 20cm.
Remove the crusts from the bread. Butter each slice on one side only and cut each slice into four triangles.
Cover the base of the dish with one layer of bread, keeping the buttered side down.
Scatter some of the sultanas on the bread and sprinkle with a little nutmeg or cinnamon, if using.
Repeat with another layer of bread, sultanas and spice, until all are used up, the final layer of bread should have the buttered side up.
Beat the eggs, milk and sugar together and pour over the bread layers.
Allow it to rest for half an hour while the bread soaks up the liquid.
Bake at 180°C/ Gas 4 for 30 mins or until just set and golden.