egg plus 1 additional egg yolk

An egg is the reproductive body produced by avian species, most commonly the domesticated chicken (Gallus gallus domesticus), consisting of a protein-rich white (albumen), a lipid-rich yellow yolk, and a calcium carbonate shell. The whole egg—yolk and white combined—represents a complete protein source containing all nine essential amino acids. Egg yolks specifically are rich in choline, lutein, and fat-soluble vitamins, while the whites consist primarily of water and ovalbumin protein. Culinary applications often benefit from separating these components due to their distinct physical and chemical properties: whites coagulate at lower temperatures and create foam when whipped, while yolks emulsify and enrich preparations.

An additional egg yolk adds concentrated fat, lecithin (a natural emulsifier), and richness to recipes. The yolk's emulsifying properties are particularly valuable in mayonnaise, hollandaise, and custard-based preparations, where the lecithin molecules facilitate the suspension of oil in water. The extra yolk intensifies color, richness, and binding capacity in baked goods, sauces, and enriched doughs.

Whole eggs serve as a foundational ingredient across virtually all global cuisines—cooked as standalone preparations (fried, poached, scrambled, baked), incorporated into batters and doughs for cakes and pastries, bound into terrines and forcemeats, and used to bind breadcrumb coatings. The additional yolk is employed specifically to enhance richness and emulsifying power in custards, crème brûlée, zabaglione, and enriched sauces like béarnaise and hollandaise. In pasta dough, pastry cream, and ice cream bases, the extra yolk deepens color and improves texture by increasing fat content and lecithin concentration. Bakers use extra yolks in recipes where enhanced richness, improved browning, and superior binding are desired.