First, sear the sausages in the frying pan until browned. This is to stop them falling apart in the slow cooker, but if you're not bothered, you can skip this.
Now chuck everything in the slow cooker OR in lidded casserole dish if cooking in the oven.
Slow Cooker: place the lid on top and leave to cook on low for 6-7 hours or high for 3-4 hours.Oven: Place the lid on top and bake in the middle of the oven at 160 degrees for around 3-4 hours.
Serve in warm bowls and sprinkle with snipped chives or whatever you fancy.
Video
Notes
For best results, sear the sausages in a frying pan first for a richer flavour and prevent them from falling apart while cooking
Before adding any liquids to the slow cooker, use it to deglaze the pan that you fried the sausages to extract as much flavour as possible