The Crêpe Nutella-Banane is the dessert crêpe that became a national habit and has not budged since. The form is straightforward: a wheat-flour crêpe is cooked on the crepière, a generous spread of Nutella is applied to the surface while the crêpe is still warm enough to melt it slightly, slices of banana are laid in a single line across the centre, and the crêpe is folded into a wedge or a roll for service. At a Parisian street cart it comes wrapped in a paper cone with the open end up; at a crêperie it arrives on a flat plate dusted with powdered sugar.
The technique is mostly about heat management. Nutella applied to a crêpe that is too hot turns thin and runs out the bottom of the fold; applied to one that is too cold it stays in stiff lines and does not coat properly. The window is the same as the one that works for the Crêpe Beurre-Sucre: the crêpe should be warm enough to soften the spread but not hot enough to liquefy it. The banana, sliced about half a centimetre thick, holds its texture against the warm crêpe; thicker slices stay too firm against the chocolate spread, and thinner slices disappear into the Nutella entirely. A good crêpière lays the bananas down in a single overlapping line so that each bite gets one slice rather than a clump, and folds the crêpe just tightly enough to keep the filling from sliding out the open end.
The combination works in part because the banana counters the sweetness of the Nutella with a slightly vegetal, fruity note, and in part because the textures are complementary: smooth chocolate spread, soft banana, slightly chewy crêpe. The variations are mostly additions rather than substitutions. A scoop of vanilla ice cream turns the crêpe into a dessert plated rather than handheld. A drizzle of chocolate sauce on top tilts the whole thing further into dessert territory. The Crêpe au Sucre and Crêpe Beurre-Sucre are the austere cousins; the Crêpe Sucrée Garnie covers the open-ended category of sweet crêpes with whatever fruit, confiture, or cream is in season. The broader Crêpe & Galette Salée tradition covers the savoury Breton end of the family, and the Nutella-Banane sits at the most-marketed, most-cited, most-eaten point on the sweet side.