The phrase
"jam layer" refers to a thick and tasty spread made from fruits like strawberries or raspberries that is often added to foods like toast or pastries to make them more delicious.
Full definition
* If you prefer strawberries you could also use frozen strawberries for the
chia jam layer.
Use
a jam layer or a chocolate crunch instead of peanut butter.
Spread the jam or preserves evenly over the crust, then crumble the remaining dough on top of
the jam layer.
The original recipe is adaptable to be either
a jam layered slice that can be cut into squares or round biscuits sandwiched together with jam.