Use brioche bread, preferably dried out overnight, or lightly toast it in the oven for 7-10 minutes until lightly toasted.
Ensure all bread pieces are well-soaked with the custard.
Gently press down on the bread with the back of a wooden spoon to ensure no dry parts.
Let the assembled bread pudding rest for at least 30 minutes before baking, or refrigerate covered overnight.
When making the buttermilk syrup, ensure the saucepan is tall enough as the mixture will bubble and foam due to the reaction between buttermilk and baking soda.