Cut the potato bread into cubes and place in the baking dish (it should be higher than the pan)
Gently beat the eggs, then add the milk, sugar, cinnamon and vanilla and continue to whip with a whisk until the sugar has been fully incorporated.
Pour this milk and egg mixture over the cut bread, mixing it well so that all of the bread has absorbed some of the milk. Let it sit for at least 15 minutes.
Add in the blueberries, distributing them through out the bread mixture. Drizzle the melted butter over the entire pan letting some of the butters richness touch as much of the top of the mixture that it can.
Cover the pudding lightly with foil. Give room for expansion.
Bake for One hour at 350 degrees, then uncover and continue to bake for 15 minutes more or until center is fully set. (if the butter has pooled in any area, spread it around before the finally 15 minutes…this will help get it golden brown.)
Allow the pudding to cool some, but serve it warm with the Creme Anglaise
Bring 4 eggs to room temperature, and separate using only the yolks.
Whip the egg yolks with the sugar until fluffy and pale yellow, set aside
In a small pot heat the milk and half and half until it is simmering, remove from heat.
Slowly mix half of the milk into the egg mixture, stirring the eggs as you pour the hot milk into them.
Add the egg mixture back into the remaining milk along with the vanilla and continue to simmer for about 5-7 minutes until the mixture has slightly thickened, use a rubber spatula to stir the mixture constantly, getting into all the corners.
(The Creme Anglaise should be thick enough that when you run your finger through a coating on a spoon it remains separated.)
You may strain the Creme Anglaise if it looks like it might have cooked egg in it, but if you're careful you should not need to. **
Place the pot with the finished sauce in a bowl of ice water to cool it down quickly, stirring as it cools.
Place the Creme Anglaise in the refrigerator to get completely chilled and serve with the warm bread pudding.
**do not get the creme anglaise too hot and don't be tempted to leave it on too long to try and continue to thicken. It will break and be unusable if it heats too long.