There are a few strategies we use to ensure our custard cake doesn't crack or end up with a weird texture. First, don't overmix the batter. Very gently fold the egg whites into the egg yolk mixture until just barely combined. Second, bake the custard cake low and slow. We keep our oven at 325F for this one. Third, don't open the oven door for at least 45 minutes. Letting in cool air too soon could cause your custard to crack.