Whisk together the flour, cornstarch, sugar, and salt in a large bowl.
Gradually whisk in the milk until the batter is completely smooth, then whisk in the melted butter and vanilla. You can also blend everything for 30 seconds instead.
Let the batter rest at room temperature for 30 minutes. This step is the secret to tender, flexible crepes that do not tear.
Heat a 10 inch nonstick pan over medium heat and brush lightly with butter. Pour in 1/4 cup of batter and immediately swirl the pan so it coats the bottom in a thin, even layer.
Cook 1 to 2 minutes until the edges lift and the underside is lightly golden. Loosen the edge with a spatula, flip carefully, and cook 30 seconds more.
Slide onto a plate and repeat with the remaining batter, brushing the pan with butter every few crepes, stacking them as you go.
Spread each crepe with chocolate hazelnut spread, add banana slices, fold into quarters, and dust with powdered sugar. A simple squeeze of lemon and sprinkle of sugar is the classic French option too.
