Put all of the ingredients in the slow cooker. With the lid off, on low, stir every 15 minutes.
When the first crust forms (this will be like a skin on the top of your mixture) stir it really well and then repeat until your second crust forms. After the second crust has formed, it's ready to pour in to your tray or mould. This will take around an hour and a half.
Refrigerate until firm, overnight is best, you can also place it in the freezer if you need it to set faster.
Notes
If you are adding alcohol, add a little bit the first time you make this slow cooker fudge recipe and if it works well then add a little more the next time you make it. If you have added too much, you can't take it out.
You do need to make sure you are stirring this often, so it isn't a hands-off recipe like most slow cooker ones are. However, you will get the best texture fudge this way.
If you are stacking the fudge in a container in the fridge, put some baking paper between each layer to stop it from sticking.