Thinly slice all the onions and place them in the slow cooker bowl. Add the melted butter and chicken stock. Cook on low heat for 10 hours.
Put the bacon slices in a medium size pan and cook on medium-high heat. Cook until crispy for about 5-7 minutes. Then remove the cooked bacon and place it on a plate lined with a paper towel and set it aside.
In a medium bowl mix the sour cream and cream cheese. Add in the cooled caramelized onions.
Roughly chop the bacon, saving a few pieces to add on top after mixing the rest in. Finally, add salt to taste. Sprinkle the top of the dip with the bacon pieces and enjoy!