Blackberry Cake

A buttermilk-and-jam spice cake of the kind that circulated on recipe cards under a contributor's name. The method as printed is compressed and leaves two things out entirely, so read the points before you start.

• The missing egg whitesOnly the yolks are accounted for in the method. Beat the four whites to soft peaks and fold them in last, after the flour; they are the lift that the single teaspoon of soda cannot supply on its own.
• The mixing order, untangledThe final sentence is telescoped. Read it as: hold back a little of the buttermilk, dissolve the soda in it, then add the flour and spices alternately with that soda-milk to the creamed base. Add the soda-milk at the end and get the cake into the oven promptly, before the reaction with the buttermilk is spent.
• No oven temperature is givenThe recipe says only 'Bake in layer or loaf'. For modern ovens, 350F: roughly 25-30 minutes for two 8-inch layers, 50-60 minutes for a loaf, testing with a skewer.
• Butter and saltThree-quarters of a cup is a stick and a half, 6 oz. Butter of this period was often salted and no salt is listed; if you use unsalted butter, add half a teaspoon of salt with the flour.
• The jamSeedless blackberry jam gives a better crumb than seedy preserve, which leaves hard specks throughout. A stiff, well-set jam is wanted, not a loose freezer jam, or the batter will be slack.
• ButtermilkCultured buttermilk from the carton is thicker and more acidic than the churn buttermilk of the period, and works well here. Plain yogurt thinned to pouring consistency substitutes without complaint.
• SpicingA teaspoon each of cinnamon and allspice with a quarter teaspoon of cloves is assertive but balanced against the jam. Ground allspice loses its edge quickly on the shelf; taste it before committing.
• Yield and finishingEnough for a two-layer 8-inch cake or one 9x5 loaf, serving 10 to 12. Layer versions of jam cake are often filled and covered with a boiled or caramel icing; a loaf needs nothing more than a dusting of sugar.