Brown the bacon in a Dutch oven over medium to high heat. Remove from the pan using a slotted spoon. Set on a few paper towels to drain the fat.
Drain all but 1 tablespoon or so of the bacon fat. Saute the onions and garlic in the fat, just until translucent. Stir occasionally with a wooden spoon. Add the butter and let melt. Add the flour and cook for 1-2 minutes, or until it's lightly browned. Stir with a wooden spoon so it does not stick to the pan.
Add the chicken stock and potatoes. Bring to a boil, then reduce to a simmer. Simmer the potatoes for 20-30 minutes, or until tender. Mash with a potato masher. Season with salt and ground pepper to taste.
Gently stir in the half and half, a little at a time. Season with onion powder, garlic powder, and ground mustard. Add more ground pepper if necessary. Stir with a spoon occasionally. Let simmer over medium to low heat for 10-15 minutes, or until the soup is thickened slightly.
Serve with a dollop of sour cream, green onion, shredded cheese and crumbled bacon.
Slow cooker:
Place the baking potatoes, chicken broth, onion, garlic, butter, salt, ground pepper, onion powder, garlic powder, ground mustard into the slow cooker. Cook on low for 5-6 hours, or until the potatoes are tender.
Mash the potatoes. Sprinkle with the flour and half and half. Stir everything together with a spoon. Continue to cook another 1-2 hours, or until the soup has thickened slightly.
Serve with a dollop of sour cream, green onion, shredded cheese and crumbled bacon.