Heat a large Dutch oven over medium heat and add the bacon. Cook the bacon until it is crisp, then remove with a slotted spoon and transfer it to a paper towel-lined plate. Reserve 2 tablespoons of drippings in the pot.
Return the pot to medium heat. Working in batches, add the sausages. Brown the sausages on all sides, then transfer them to a plate.
Add the onions to the pot and cook until they are slightly tender, about 3-4 minutes. Pour in the cider to deglaze the pot, scraping the bottom of the pot with a spoon.
Cut the sausages into 2-inch pieces and layer them on top of the onions. Scatter in the bacon, thyme, parsley, and bay leaves. Layer the potatoes and carrots on top of the sausages and herbs. Pour in the beef stock and season with black pepper.
Bring the pot to a gentle simmer, then tightly cover it and transfer to the oven. Cook for 2-2½ hours, until the potatoes are extremely tender. Remove the thyme sprigs and bay leaves before serving.