In a large Dutch oven over medium heat, cook the bacon until it is crisp and golden brown, about 4 minutes. Using a slotted spoon remove the bacon from the pan and transfer to a plate.

Increase the heat to medium-high and cook the beef in batches until it is browned on all sides, 2 to 3 minutes per side. Transfer the beef to the same plate as the bacon.

Add the mushrooms to the pan and cook until wilted and beginning to brown, and then add the onion, celery and carrot and cook for another 3 to 4 minutes or until the vegetables are tender.

Add the flour and stir well, cooking for 2 minutes longer.

Add the garlic, Guiness, beef, beef broth, thyme and bay leaf and bring to a brisk simmer, stirring occasionally. Cook the stew, covered and stirring occasionally,  over medium-low heat, for 1 ½ hours or until the beef is tender. If necessary add a little more broth to keep the stew from getting too thick.

Serve the stew with Champ and garnish with the chopped parsley.