Preheat oven to 200°C / 400°F in fan grill setting.
Drain canned pineapple and dice into 0.5 inch cubes, then transfer to a baking dish. Sprinkle cinnamon all over and toss to combine. Grill in the oven for 4-5 minutes.
Stack the tortillas up and wrap them in a packet of aluminum foil. Place in the oven for 10 minutes or until warmed up. You can do this at the same time as the pineapple.
Dice chicken into bite sized pieces.