It came as a minor revelation to me that my massive collection of Bon Maman jam jars could be put to use as freezer containers rather than taking up space under the stairs. I have always been wary of freezing glass since the day I froze ditch water in jam jars as a child and then, when sitting them on hot concrete, was horrified as they shattered. It's all to do with the conduction of heat, or something, so as long as you sit the frozen jars on something like a chopping board when it's defrosting all should be well.
Usually I make and freeze an easy tomato sauce for use on pasta or in lasagne. It's easy but involves slow and long cooking so it's not one I can whip together easily before dinner…hence the freezing.
I use the food processor to chop up a load of onions, carrots, celery and garlic and then let them sweat away gently in lots of olive oil before adding in a couple of bay leaves, fennel seed, oregano, thyme, rosemary and black pepper. Once it's all soft I cook off some red wine then add a carton of passata and a can of chopped tomatoes and then let it simmer gently until I feel it's done…maybe an hour.