Using a reliable non-stick pan, brown the planned-over chicken breast medallions, and then put cheese over the top to melt. This is Provolone. The cheese that spills over onto the pan should brown to a pleasant, nutty taste that adds a lot to the flavor of the sandwich. Watch that it doesn’t burn.
The next day for lunch, we had the remainder of the chicken fixed quite similarly, but with two changes. I added leftover, cooked broccoli in small bits over the White Cheddar cheese as it melted on top of the chicken. It melded with the Cheddar, so was easy to transfer to the sandwich bun.
Best to toast the bread separately before assembling the sandwich. It will get overdone if you expect to have it under a broiler long enough to heat the chicken through and melt the cheese.
This could easily be served over a smallish-shaped pasta with good results, too. Any whole grain would add a lot of nutrition. I had planned-over quinoa in the refrigerator, but didn’t think of serving it on that until just now as I iterated the possibilities.
Try this method with any kind of leftover meat and vegetable that seem compatible to you. You can also make it up as a panini, but doing it open-faced like this keeps the calorie count in check by using only half a bun. In fact, I had cut this bun into three lengthwise slices because it was so thick to start with.