Gâteau breton is a thick, close-textured butter cake of flour, sugar, egg yolks and a great deal of salted butter, scored in a lattice and baked until deep gold.
The cake was developed in the Lorient area in the second half of the nineteenth century as a keeping cake for sailors and fishermen: high in butter and sugar, low in moisture, it lasted weeks at sea. The classic proportions run close to equal weights of flour, sugar and butter, bound with egg yolks alone rather than whole eggs, which is what gives the crumb its short, almost shortbread density. The criss-cross scoring on top, brushed with yolk before baking, is the standard finish. Some versions carry a layer of prune paste or salted-butter caramel through the middle; the plain one is the original.
