When Brownies Crack on Top?

When the batter is put into the oven, air bubbles expand with the heat. Once they come out of the oven, those air bubbles collapse after they are shocked by cold air and cause cracks. The more air bubbles you have in your batter, the more cracks will form when those air bubbles collapse.

Why is my Brownie breaking?

When you beat the eggs and butter you incorporate air into them, and the flour stabilizes the air bubbles. But if too much air is in the mixture for the amount of flour, the brownies "over-expand" as they bake, but collapse, or cave in, as they cool and the unstable air bubbles deflate.

Are brownies done when they crack?

As with most baked goods, the amount of time brownies spend in the oven can make or break them. ... Katzie Guy-Hamilton, Global Director of Food and Beverage of chocolate heaven Max Brenner, told Epicurious that once the top is shiny and set (not "wiggly"), the first cracks are a telltale sign that your brownies are ready.