For example, think of this as icing: A company reports excellent quarterly earnings, but its share price doesn't change that much because of other factors such as a slowing economy, increased competition, or high interest rates were expected, i.e., baked in the cake.
Of course, a company could get hit with awful news before an earnings report -- say, the equivalent of weevils in the flour or a nonlethal strain of salmonella in the eggs. In that case, the price of shares also might not move that much after the earnings report. Again, the results were baked in the cake, and no one was particularly surprised by them.