This is what we had for supper last night; it's a way of making one packet of sausages feed 4 - 6 people.
Preheat the oven to 180C (fan)
So; you will need (quantities are variable)
an onion chopped smallish - or a leek if there's one lying around
a couple of sticks of celery, also chopped smallish
a clove of garlic (optional) crushed.
a carrot or two, chopped smallish
if you've some red or green or orange or yellow pepper, or a courgette, then chop it up and chuck it in
gently fry all that lot in a small amount of oil until the onion is transparent and it smells good.
Then tip it into a shallow oven-proof dish, along with a tin of chopped tomatoes. Half fill the empty tin to rinse out the tomatoes and add that as well. Some seasoning - a stock cube or stock powder or soy sauce or even a bit of salt, (remember, the sausages will probably be fairly salty so you won't need much), and maybe some herbs, a bay leaf, and a grind of pepper. A spot of pesto doesn't hurt, if you have some left in the jar.
Depending on your mood, either cut each sausage into four, (quick and theraputic) or slit each sausage, remove the skin and make each one into at least 4 meatballs (good if you need to feed a weird number of people like 5, or even 6 people from one packet of sausages. Just do a bit of arithmetic).
Lob the bits of sausage into the dish with the rest of the ingredients, and bake for round 40 mins. I usually take a look after 30 mins and maybe turn all the meatballs over, as the tops will have browned but underneath often looks a bit pale.
Serve with pasta, or baked potatoes, if you remembered to put them in before you started.