Apparently seed cake was very common and is very old. The recipe below is for a sweet one, but look how much butter is in it!
“…[O]lder recipes of a ‘bread’ type seed cake i.e. more bread than cake, made with yeast to help it rise, go back hundreds of years, with a variety of seeds as their main ingredient, and using suet, lard or fat instead of butter. In our recipe we are using the caraway seed to flavour the cake, (giving an almost sweet aniseed taste). Caraway is a type of seed common to both cake and biscuit recipes of the Medieval and Tudor periods; and the English usage of the term Caraway dates back to at least 1440 A.D.”
A Very Good Seed-Cake: 1861
From Mrs. Beeton’s ‘Household Management’
1 lb. of butter, 6 eggs, 3/4 lb. of sifted sugar, pounded mace and grated nutmeg to taste, 1 lb. of flour, 3/4 oz. of caraway seeds, 1 wineglassful of brandy.
Mode.—Beat the butter to a cream; dredge in the flour; add the sugar, mace, nutmeg, and caraway seeds, and mix these ingredients well together. Whisk the eggs, stir to them the brandy, and beat the cake again for 10 minutes. Put it into a tin lined with buttered paper, and bake it from 1–1/2 to 2 hours. This cake would be equally nice made with currants, and omitting the caraway seeds.
Time.—1–1/2 to 2 hours.