Grease a deep 10 cm x 20 cm or 4-inch x 8-inch baking dish with butter. Place a rack in the middle of the oven and preheat the oven to 180 °C or 350 °F.
soak the bread
All ingredients should be at room temperature. In a bowl, whisk to combine the eggs, milk, melted (and cooled) butter, sugar, a pinch of salt, vanilla paste, and cinnamon powder. Cut the bread into 1 cm (1/2 inch) slices. Soak each bread slice in the mixture separately. Ideally, leave it to soak for a couple of seconds and up to a minute. This is essential to ensure a moist texture.
Drain the bread and arrange it in the prepared baking dish. Pour the vanilla mixture over the bread. Place the baking dish over a baking sheet and place it in the preheated oven in the middle rack. Bake for 40 - 45 minutes at 180 °C or 350 °F or until golden brown.
When the bread pudding bakes, remove it from the oven and set aside for a few minutes. Before serving, dust with powdered sugar then cut into slices and serve with fresh berries, if available.