toast the bread cubes for 8-10 minutes to dry them out. Alternatively, you can use day old bread that is already dried out.
Increase oven temperature to 250F
Heat oil in a sauté pan. Add the sausage, apples onions and celery, and sauté for 5-7 minutes, until everything is heated through and the veggie are tender. Allow to cool a few minutes before continuing.
Place all ingredients in a large bowl and toss to throughly combine.
Spoon the stuffing mixture into greased muffin tins, filing all the way to the top. Pat the mixture down to pack it week.