Be sure to grease the custard cups with shortening and dust the cups with cocoa. Baking the cakes at the correct oven temperature for the right time are critical to the success of this recipe. If the centers are too cakelike in texture, bake a few minutes less the next time; if they’re too soft, bake a minute or two longer.
To make ahead, pour the batter into custard cups, cover with plastic wrap and refrigerate up to 24 hours. You may need to bake the cakes 1 to 2 minutes longer.
Do not use self-rising flour.