Heat the oven to 325℉
Wash and slice the potatoes ½" thick. I like to cut the potatoes in half, then cut into them slices. You do not need to peel the potatoes if you are using Yukon Gold.
Peel the onion, cut it in half, then into thick slices.
Clean and slice the leek. Cut off the dark green leaf end, then slice into ¼" slices. Submerge the sliced leeks in a bowl of cold water. Gently stir or shake to remove any soil or grit between the layers.
Chop the bacon and add it to a hot Dutch oven set over medium heat. Cook, stirring frequently, until crisp, then remove from the pan with a slotted spoon and drain on a paper towel.
In the same Dutch oven cook the sausages just until they start to brown, but not so they are cooked all the way through. Remove the sausages from the Dutch oven and set aside. Discard any leftover bacon fat in the bottom of the Dutch oven. Pour out any leftover grease.
Cut the sausages into ½" slices.
Layer half of the sliced potatoes on the bottom of the still-hot Dutch oven, then layer half of the sliced onions and leeks over the potatoes. Season with salt and pepper, then sprinkle half of the bacon and half of parsley. Repeat with the remaining potatoes, onions, leeks, salt and pepper, and add the remaining bacon and parsley. Nestle the browned sausages on top and pour the chicken broth over everything.
Cover the Dutch oven with a lid and place it in the oven. Bake for 1 ½ hours. Take the lid off and continue cooking for a half hour, or until the potatoes are cooked through. Check the pan to ensure the liquid hasn't all dried up. Add an extra cup of broth if necessary to keep about 1 inch of liquid covering the bottom of the pot at all times.
If the stew is too brothy, mix two teaspoons of cornstarch with ¼ cup of water and stir into the pot to thicken during the last half our of cooking.
Ladle into bowls and serve with soda bread.