Combine flour, sugar, baking powder, salt and cinnamon in a large mixing bowl. In a separate bowl, whisk the milk, egg, oil and vanilla extract (if using). Add this to the dry ingredients and stir well until fully incorporated.
Mix in the banana and (optional) chocolate chips. Stir well until combined. Lightly oil a skillet and preheat over medium heat. Ladle desired amount of batter into the pan (about 1/3 cup for each pancake). Cook until small bubbles appear on the surface, then flip to cook the other side. Cook until both sides are a light golden brown. Repeat until all of the batter is used. (You may need to lightly oil the pan between batches.)
Serve warm with butter and maple syrup, honey or jam spread on top.