Beat eggs in a mixing bowl until frothy, about 2 minutes. Add flour, milk, baking powder, and vegetable oil to the eggs and mix to make a batter. Stir mashed bananas into the batter.
Ladle batter in 1/4 cup portions onto hot griddle. Cook until tiny air bubbles form on top, 2 to 5 minutes; turn and continue cooking until the bottoms are browned, 2 to 3 minutes. Repeat with remaining batter. Keep finished pancakes warm. Top pancakes with banana slices and maple syrup to serve.
