Génoise is the foundational whole-egg sponge of French pâtisserie, relying entirely on the aeration of eggs and sugar over a bain-marie to achieve its characteristic open, springy crumb. The method begins by whisking whole eggs with caster sugar over water held at 50-55°C until the mixture reaches 40-43°C and triples in volume — the ribbon stage, where a trail of batter holds its shape on the surface for 5-6 seconds. This thermal step denatures egg proteins just enough to stabilize the foam without coagulating them prematurely. Once the sabayon is removed from heat, high-speed whisking continues until the bowl is cool to the touch and the foam is thick, pale, and voluminous. Sifted flour — typically Type 45 or a soft cake flour at 7-9% protein — is folded in thirds using a large balloon whisk or spatula, cutting through the centre and sweeping along the bowl's wall to preserve air cells. Clarified butter at 40-45°C is tempered with a small portion of batter before being folded into the mass; butter added too hot or too cold collapses or streaks the foam. The standard ratio is 4 eggs : 125 g sugar : 125 g flour : 40-60 g clarified butter. Baking occurs at 175-180°C in a prepared mould for 25-30 minutes, until the cake pulls slightly from the sides and springs back when pressed. Underbaking yields a gummy band; overbaking dries the crumb and compromises its ability to absorb syrup. A properly executed génoise serves as the structural layer for entremets, charlottes, and layered gâteaux, absorbing flavoured syrups without disintegrating — a quality directly tied to the uniformity and stability of its foam structure.
Warm eggs and sugar to 40-43°C to maximize foam stability before whipping; fold sifted flour in thirds to maintain aeration; temper clarified butter at 40-45°C with a portion of batter before incorporation; bake at 175-180°C until the cake just pulls from the mould sides; allow full cooling on a rack before slicing or soaking to prevent structural collapse.
Weigh eggs out of shell — 50 g per large egg ensures batch consistency; line the mould bottom with parchment but leave sides ungreased so the batter clings and rises evenly; invert the cake immediately on a wire rack to prevent the base from steaming and becoming gummy; wrap tightly and rest overnight before assembly — the crumb firms and absorbs syrup more uniformly.
Overheating the egg-sugar sabayon past 50°C, causing premature coagulation and a dense crumb; adding butter directly without tempering, which deflates the foam by up to 40%; using high-protein flour that develops excess gluten and toughens the sponge; undermixing flour so pockets of dry starch remain; slicing the cake while still warm, compressing the crumb irreversibly.
Escoffier, Le Guide Culinaire; Lenôtre, Faites Votre Pâtisserie Comme Lenôtre; Hermé, Pâtisserie