I prepare BM in a tub that lasts the blogger and me for nearly a week. Here is how I prepare it:
I place 4 cups of rollead oats in a container
I add half a cup of crushed walnuts (optional)
I add 1 teaspoon of nutmeg and 1 teaspoon of cinnamon
I add 3 cups of orange juice
I add 1 tub of yoghurt natural or fruit whatever I find in the fridge
Sometimes I grate an apple into it at the end but as we always top it with fresh fruit salad before we tuck in, that's not necessary.
Of course you can prepare more or less, depending of your needs. But it is important to leave it overnight. as it gets better and smoother as the week goes on.