When you bake in glass canning jars, those home-baked treats are available even on days when you are too tired or too busy to create something in the kitchen. Sealing the cakes in the glass jars also allows you to mail them to friends and family. Tuck a jar cake into a package for a deployed service member to send a taste of home.
Wash and sterilise the jars and rings in the hottest setting on the dishwasher. If you do not have a dishwasher, wash them thoroughly and then submerge them in boiling water for 10 minutes.
Place the lids in a saucepan and add enough water to cover them. Bring the water to a slow simmer.
Grease the inside of the jars. Keep oil off the jar rims or the lids will not seal properly.
Add 237 ml (1 cup) of batter to each jar. Do not overfill the jars, or the cake will rise too high for proper sealing.
Place the cake pan in the oven. Set the jars in the pan to steady them on the oven rack.
Bake the cake according to the recipe or package directions. Check for doneness by inserting a toothpick into the centre of the cake. If cooking is complete, the pick will come out of the cake clean.
Remove one jar at a time from the oven. Place a lid on the top of the jar. You may have to push the top of the cake slightly. Add a ring and tighten it to seal the jar. Repeat until all jars are sealed.
Store the jars on a shelf in the same way that you would other home-preserved food. If you are unsure of the sealing of the jars, store the cooled cakes-in-a-jar in the freezer.
It is important that the cake cook thoroughly. Follow the recipe's regular baking temperatures to be sure that the heat kills bacteria.