Preheat your panini maker.
Slice bread in half. Spread pesto to taste on each side.
Layer on chicken, tomatoes and cheese to taste. I always prefer it very thin but you can stack your heart away! Just remember that you are pressing this and it may fall apart while it's pressed down if too thick.
When ready, spray panini maker with the olive oil spray.
Place sandwich on press and push down to desired thinness and let sit until desired toast.