Preheat the oven to 180C/160C fan/Gas 4. Butter an ovenproof dish.
Butter each slice of bread and cut into triangles. Arrange a layer in the dish, then scatter over half the raisins and a sprinkle of cinnamon.
Repeat with another layer of bread triangles and the remaining raisins.
Beat the eggs with the milk, sugar and vanilla extract. Pour the mixture evenly over the bread.
Leave to soak for 10 minutes so the bread absorbs the custard. Press down gently to help it along.
Sprinkle the top with a little extra sugar and grate over some nutmeg. Bake for 30-35 minutes until puffed up and golden on top.