In a medium bowl, whisk together flour, sugar, baking powder, salt, and cinnamon.
In another medium bowl, mash 2 bananas. Whisk in milk, peanut butter, egg, and vanilla.
Add wet ingredients to the dry and whisk just until combined. Stir in chocolate chips. The batter should be thick yet pourable.
Slice remaining 2 bananas and set aside.
Heat a 12-inch non-stick skillet or griddle over medium heat. Grease a paper towel with oil and use it to brush the pan. Use a ¼ cup measure to pour batter onto the skillet. Scatter 4 slices of banana onto the surface of each pancake.
Cook until small bubbles appear on top and the undersides are golden, about 2 minutes. Flip and cook until golden on the second side, about 1 minute more. Repeat process with remaining batter.
Serve pancakes warm topped with peanut butter and maple syrup.