Here is my method (I call it a method rather than a recipe as it is pretty basic and you can adjust quantities to suit).
Slice enough bread to cover the base of a baking dish. Butter each piece.I use real butter for flavour and richness. I put mine angled against each neighbouring slice to create depth and interest plus a nice pocket underneath for the egg custard to lurk. Sometimes I sprinkle a little sugar over the top at this stage, other times I just add sugar to the egg mixture. A variation is to sprinkle sultanas or raisins through the sliced bread. Try not to let them sit on top though as they may burn.
To make the egg custard, add one egg for each cup of milk and roughly a tablespoon of sugar for each 2 cups of milk. add vanilla essence to taste. whisk until combined and the sugar is dissolved.
Pour the egg mixture over the sliced bread. I like to have enough to still have plenty of mixture around the bread after it has soaked in so there is some eggy custard.
I love to grate fresh nutmeg over the top. It really is worthwhile using a whole nutmeg and grating it yourself. It doesn't take long and the aromatic difference is amazing.
Bake in the oven on a lowish to moderate temp, around 150celsius until the top puffs and the middle is no longer runny. It will still be a bit jiggly but usually if the centre is cooked it will be puffed evenly.
It will sink again as it cools.
If you try and cook it fast and too hot, the custard will curdle and separate. (How do you think I know this?)
Serve warm in winter or cool in summer with preserved fruit. We love it with tinned peaches or stewed apricots.
Other variations are to use spicy yeast buns or those big boston buns you often get cheap at the supermarket. Any kind of plainish butter or sponge cake will also work for a sweeter richer dessert.
If you live in Adelaide, SA, you can buy whole nutmeg (and a huge selection of imported and local herbs, spices and delicacies and bread flours) in bulk at Gaganis Brothers on south Rd at Hindmarsh (parking at rear).
I bought a big bag of nutmeg and have had it stored in a tin for over 10 years and it cost me $5.00 back then. They still have a wonderful flavour. I should bake more spicy stuff.