M.G.
have you tried Magic bars? Those are very popular. I have made those and froze those before. They are the kind of bars you get the recipe for on the back of the tins of condensed milk cans.
You can omit the nuts if that would cause concerns with allergies.
When I have done them - I just cut them into bars, and froze them in a container separated with wax paper between the layers. There probably is more effective ways to do this - I usually am pretty harried by the time I get my baking done.
However, they are very moist and chewy and mine were not affected by being frozen. I just yanked them out and served them on a plate (left them to defrost), and tasted the same.