Preheat oven to 180 C or 350 F. Grease an 8x11 or 9x13-inch baking dish.
Melt butter in a large frying pan or skillet over medium-high heat.
Add onions, celery and garlic. Sauté, stirring occasionally, for about 4-5 minutes or until the onions are soft and leeks are tender.
Add stock or broth. Stir. Simmer for about 3 minutes.
Add croutons, eggs, dried cranberries, thyme, sage and rosemary. Stir to combine. Season with salt and pepper.
Transfer stuffing mixture to the baking dish.
Bake, covered, for about 40 minutes or until the middle sets and top turns crisp and golden brown.