“Biscuits should be crumbly, buttery and sweet,” reads a headnote for acinnamon sugar-spiced shortbread recipe in theRitz London Cookbook. The recipe includes a peculiar instruction with no explanation: Boil an egg for 10 minutes, remove the yolk, and grate it into the dough.
Molecular biologist and cookbook author Nik Sharma first happened upon this instruction when developing his recipe forSpiced Golden Shortbread Cookies. He decided to do his own research.
As it turns out, adding hard-boiled egg yolks to your biscuit dough is a way to ward off an overworked, tough dough that can be the downfall of a butter-based pastry. When the trick is employed, the pastry shatters and then dissolves in your mouth quickly, tasting like a knob of flaky butter.
Photo by Joseph De Leo, Food Styling by Rebecca Jurkevich
Sharmaexplains that raw eggs are “about 50% water; during boiling, this water participates in the chemical and physical changes inside the egg…and is no longer readily available. As the egg and yolk proteins denature and solidify, they form a mesh and squeeze their water out.” Sharma says that this cooked egg “mesh” becomes kind of like a raincoat preventing water from coming in and drenching your outfit. When the small dustings of cooked yolk are sprinkled throughout the dough, they get in the way of strong, overly chewygluten formation.
The technique, as it turns out, has been around much longer than theRitz London Cookbook. New York restaurant owner Larry Forgione learned about this same technique when his friend James Beard shared his mother’s recipe for shortcake as the two were relaxing in Beard’s townhouse. Forgione was so intrigued by the shortcake’s perfectly tender crumb that he put it on the menu at his influential Manhattan restaurant, An American Place, which opened in 1983.
Pastry chef and cookbook author Claudia Fleming first learned about this technique in a professional kitchen from the former pastry chef at Union Square Cafe, where Fleming worked in the late ’80s.In her cookbook,Delectable, the technique comes into play in arecipe for blackberry shortcake. Here, Fleming uses typical shortcake ingredients such as all-purpose flour, baking powder, salt, butter, sugar, turbinado sugar, and heavy cream, but she adds two hard-boiled yolks to her dough mixture. The resulting texture is soft and buttery.
