Lightly grease your tin with butter or nonstick cooking spray.
Put the eggs, pumpkin puree, pumpkin spice, sugar, vanilla, cream and milk in a bowl.
Whisk together to make your custard, then set aside.
Cut each slice of bread in a 4 by 4 pattern to give cubes around 2 cm (3/4 inch) in size. Pile them into the prepared tin.
Scatter the sultanas on top and give everything a little bit of a mix with your hands to distribute them.
Pour the custard into the tin, aiming to coat all of the bread chunks evenly. (If you like, at this stage you can place the tin in the refrigerator, ready to bake in the morning.)
Mix the demerara sugar and pumpkin spice together and sprinkle all over the top of your bread chunks.
Bake for 50-60 minutes until the top is crisp and the casserole is set through.
Cut into squares to serve. I recommend serving with maple syrup and whipped cream.