In a mixing bowl, combine flour, sugar, and a pinch of salt. Create a well in the center.
In another bowl, whisk together eggs, milk, melted butter, and vanilla extract until well combined.
Pour the wet mixture into the well of the dry ingredients gradually, whisking until the batter is smooth and lump-free.
Let the crepe batter rest for 30 minutes at room temperature.
Heat a non-stick skillet over medium heat and lightly grease with butter.
Pour about 1/4 cup of the batter into the skillet, swirling the pan to coat the base evenly.
Cook for about 2 minutes, or until the edges start to lift and the bottom is lightly golden. Flip the crepe and cook for an additional minute on the other side.
Repeat with the remaining batter, stacking the finished crepes on a plate.
To serve, spread Nutella on one half of each crepe and layer sliced bananas on top. Fold the crepe in half, then half again to create a triangle.
Serve warm, topped with whipped cream and a sprinkle of chopped hazelnuts if desired.