Pound cake, unlike other cakes, is supposed to crack on top as it bakes. This is primarily because the batter is very dense. The dense batter requires a very looking cooking time to bake all the way through, and the exterior of the cake sets up before the interior does. As the cake continues to bake, the majority of the heat/steam being released from the still-baking cake comes up through the top and center of the cake after the sides have set. A big crack right down the center of a loaf can give a pound cake a very dramatic look – but the crack doesn’t usually appear perfectly centered on its own in a cake. Fortunately, there is a trick that can help you guide the crack and get it where you want it to go.
The trick to getting a perfectly cracked pound cake is butter. You simply create a line of butter on top the cake batter before it goes into the oven and the cake will crack open along it. You can do this in one of two ways: using melted butter or solid butter. If you are using melted butter, you can dip a knife or bench scraper into the butter and run it along the top of the cake batter in the pan. If you are using solid butter, cut a very thin strip (1/8-inch thick, or even less if you have good knife skills) and lay it on top of the cake. I usually go with the cold butter-option, since it’s easy to cut a very narrow slice (or a few narrow slices) from a stick of cold butter.
Not everyone likes the look of a cracked pound cake (and many people grew up with commercial cakes that had perfectly smooth tops) and that is ok if you want to aim for that using cake strips or by lowering the oven temperature. That said, since pound cakes are supposed to crack, it’s nice to know how to control the cracking so that you get the best looking finished cake possible. You can also use this technique on other loaf cakes – such as lemon breads – that might tend to crack open as they bake for a nice finished look, too.