my bread sauce starts with half a small onion (a shallot would work too) really really finely chopped, into a pan of milk with a bay leaf, parsley stalks, little bit of celery and a single clove...tie it all in together if you like...like a bouquet garni If you are not keen on the onion being left in then you can leave it in bigger bits and pick it out with the herbs later
I heat that to a boil and then just let it sit until it is cool, pick out the herby bits
Then I break some nice bread into small pieces and drop them into the milk, I don't use breadcrumbs as I think that makes it gluey, if you bash about with a wooden spoon the bread will disintegrate anyways
bring it back to a high heat and keep stirring, and then I let it down with single cream...also at this point add in plenty of S&P and a really good grating of fresh nutmeg
I do mine the day before, it will thicken dramatically overnight, but it will reheat nicely in the micro, and you can always stir in some more cream to let it down again...it wants to be a nice dolloping texture, not runny, sort of like cake mixture
i make mine is a small milk pan, with a couple of slices of bread...and I really really like it in a turkey and ham sandwich spread on the turkey like mayonnaise.