Mash 2 bananas in a medium bowl; slice remainder of banana and set aside slices.
Whisk eggs, vanilla, baking powder, cinnamon, and grapeseed flour into bowl with bananas until blended.
Coat a large nonstick skillet with grapeseed oil; set over medium heat.
Spoon 2 Tbsp batter for each pancake into skillet. (You may need to do this in 2 batches.)
Cook over medium heat until edges are set and bottoms are golden, about 1 minute. Carefully flip pancakes with a thin spatula and cook on other side until bottoms are golden, about 1 minute.
Serve pancakes topped with berries, reserved sliced bananas and dusted with powdered sugar.