Rinse your chicken under cold water and then pat dry with a paper towel. If you have a chicken that is roughly prepared, just remove the giblets, etc and then clean and pat dry.
Season the outside and inside of your chicken generously with salt and pepper and then place the chicken in the crockpot. It does not matter how you place it in there but lets keep it simple, just like it would sit on a shelf is what it should look like in your crockpot.
Chop up 2 sprigs of rosemary and depending on how you zested your lemon, chop that up too.
Place the rosemary, lemon zest, lemon juice, honey, and dijon mustard in a bowl and mix well. If your honey is thick you can microwave it for 15 seconds or so to soften it up and help it mix.
Place your remaining sprig of rosemary, the quartered onions, the garlic, and the lemon halves inside the cavity of the chicken.
Now using a brush, take your honey dijon mixture and brush all over the chicken and coat heavily, you should use all of i.t
Now cook on low in the crockpot for 6 hours
Serve with anything you like or just eat the whole chicken like I plan on doing.
Be very careful when you are removing your chicken from the crockpot, it is gonna want to just fall apart from being so tender so carefully remove it if you are trying to plate it or serve it on another dish, if not let all the meat fall off the bones and enjoy