the mcgriddle from mcdonalds contains a pancake bun but it is made with syrup in the bun. its very similar, if you hollow out the gap by making two layers the syrup could be possible but you would need alot to make it... an improvement would be a injection maybe. like a plastic plunger vial with syrup inside. production costs wouldnt be as much and it would be easy to assemble because you just throw the vial with the pancakes in the box.
(if the syrup was in the hollow pancake already, it would absorb and be soggy. the vial ensures the syrup is freshly put on.)
