In a large bowl, mix the oats, milk, oil, banana, eggs, and 1/2 cup of the reserved pineapple juice.
Mix flour, baking powder and salt. Add to oat mixture. Beat well.
In a small saucepan, blend the cornstarch and syrup until smooth. Stir in 1/2 cup reserved pineapple juice.
Cook, stirring constantly, for 2-3 minutes until syrup begins to thicken. Stir in pineapple pieces and remove from heat.
Heat griddle (when a drop of water dripped onto the griddle sizzles, it's ready). Spray lightly with cooking spray. Pour batter onto hot griddle, about 1/4 cup per pancake. Cook until batter bubbles and edges begin to look dry. Flip and cook until golden brown.