Heat the oil in a large frying pan, saute the onion until softened (about 5 min).
Squeeze the sausage meat from the sausages into a large bowl, then add all of the other ingredients (including the onions),EXCEPT the cranberries and streaky bacon, seasoning well; mix together well by hand.
(Weigh out 450g of the stuffing and mix a handful of the cranberries into it, then pack this up to use as stuffing for a turkey or to bake on its own. The rest will be used to make the two stuffing rolls).
To assemble each roll, butter and season a large sheet of foil. Stretch out the bacon rashers slightly with the back of a kitchen knife, then overlap 12 rashers on the foil making a big flat rectangle of bacon strips.
Spoon half of the stuffing mix evenly over the bacon, leaving a border of about 3cm. Scatter with half the cranberries, then pat the down with your fingers.
Tuck the long edges of the bacon over the stuffing; then, using the foil to help, roll the stuffing up into a log shape. Repeat to make a second roll. If you like things neat and tidy, you can also using a few pieces of kitchen twine to help hold the roll together.
Seal each log in greased foil.
(At this point you can freeze your logs up to 1 month. Thaw before serving and cook up to 1 day in advance, reheat before serving,or just roast on the day you are serving).
Heat oven to 190C/fan 170C/gas 5. Put the foil-wrapped rolls onto a roasting tin and roast for 45 minutes Unwrap, draining off any juice, then finish roasting for 15 mins until the bacon is crisp.
OAMC instructions:The rolls can be prepared up to 2 days ahead and kept, raw, in the fridge, or frozen for up to 1 month. Roast up to 1 day ahead, then reheat, wrapped in foil, for 30 mins while the turkey rests and your vegetables finish cooking. The third portion can be baked in a casserole using the same temp/times as the logs.