Wash the apples and remove the skin. Then chop them into bite-sized pieces.
Add the sugar and stir well. Set the apples aside.
Combine oats, baking mix or flour, brown sugar, cinnamon and slowly add in soft butter. Trust me on this one - don't melt the butter or try to add in cold butter. It just doesn't work well.
Layer oats mixture, another layer of apples, and more oats on top. Fill the jar as much as you can because you'll be surprised at how much it sinks during baking, making you think that the recipients will rename your gift "Half of an Apple Crisp in a Jar."
Bake at 375 degrees for 20-30 minutes. I just looked for browning, then pulled them out.
I refrigerated these for a night, and then put them and some mini containers of vanilla ice cream (to fill the other half of the jar that had settled) into a big cooler bag and brought them to the school for the boys' teachers.
*As a rule, oats are gluten free, but the areas in which they are grown may have been previously occupied by wheat. It's safest to use gluten free oats if you have a wheat allergy.