Loaf cakes and quick breads taste pretty good no matter their appearance, but sometimes you want that perfect, professional looking line down the center, signaling to everyone who gazes upon it that you’re a baker who knows what they’re doing.
Pound cakes and the like crack on top because their batters are so dense. In fact, it would be weird if they didn’t. The outside of the cake sets first while the inside continues to cook, eventually rising up and pushing through the crust. Some people try and prevent crackage by baking their cakes at lower temperatures or in a tube pan instead of a loaf pan, but I’ve always thought the crack looks rather nice—embrace the crack, people!—especially if you can get it to appear straight down the center.
Without guidance from you, the baker, that line’s appearance can be unpredictable, and it may not pop up right in the center. (I don’t know about you, but I prefer a symmetrical, evenly baked baked good.) The key to controlling the line, like so many things, is butter. As Edd Kimber, winner of the first season of the Great British Bake Off, explains on his Instagram (@theboywhobakes), introducing butter to the top of the cake creates a “break” in the batter, encouraging the split in that precise location.
You can use a knife or a bench scraper to do it. Just dip or brush either implement in melted butter and then dip or drag it through the batter. Some people set thin slivers of cold butter directly in the batter, which also works. I suspect olive oil or another fat would work as well, if you want to keep things dairy-free. Once your line of fat is in place, just bake as usual. Your cake or quick bread will form a cute little butt, and you can take lots of pictures to show off your skills.
h/t The Kitchn