Blend batter (first 9 ingredients) together in blender.
Heat non-stick pan over medium low on stove. Add cooking oil and swirl pan to coat.
Pour batter into pan, about 1/4 cup for an 8-inch pan. Pick up pan from the burner and tilt to spread the batter around the bottom of the pan. Moving it in a circular tilting fashion will spread the batter out evenly. Batter should go to the ends of the bottom part of the pan.
When the top is noticeably cooked (1-2 minutes_, flip the crepe to lightly brown the other side.
Repeat process to cook the remaining crepes, setting finished crepes on plate with parchment paper between them to prevent sticking.
Spread Nutella over one side of the crepe, add bananas and either fold or roll up to serve.