Put the bread in a heatproof bowl and pour in boiling water to cover. Let soak for 5–10 minutes. Remove the bread and gently squeeze out as much of the moisture as you can.
Meanwhile, put the shallot and mace blades into a tea infuser (or tie them in a square of cheesecloth). Pour the milk into a small saucepan, add the tea infuser, and heat over medium heat to just below boiling. Remov