Spread the bread cubes onto a large baking sheet in a single layer and bake until lightly golden brown, about 15-17 minutes. Remove from oven and let cool.
In large saucepan, cook bacon over medium high heat, stirring occasionally, until it starts to crisp up and the fat has rendered, about 10 minutes. Using a slotted spoon, transfer bacon to a paper towel lined plate. Reserve 3 tablespoons of bacon fat from the saucepan and discard the rest.
Reduce heat to medium. Add the leeks to the bacon fat and cook until soft, about 3 minutes. Add Brussels sprouts and cook for 5 minutes, until soft. Stir in mushrooms, salt, and pepper and cook until mushrooms release juices, about 5 to 10 minutes.
Turn heat to high. Add beer and cook until liquid reduces by about half.
Place bread cubes in a large bowl. Add in vegetables, bacon, oregano, thyme, parsley, dried cranberries, and whisked eggs. Stir to combine.
Transfer stuffing to a 8 x 11 x 2 inch baking dish. Evenly pour stock over entire dish.
Cover baking dish with foil and bake for 20 minutes. Remove the foil and continue baking until the top is golden brown, about 30 to 40 minutes longer. Remove from the oven and let cool for 10 minutes before serving.