I like to start checking the cake at about 40 minutes. If the edges are looking dark, darker than the rest of the cake, tent the cake with a large piece of foil (being careful to not let the foil touch the cake). Test the cake by inserting a skewer or toothpick into the thickest part of the cake. There should be a few moist crumbs on the skewer. If there is wet batter on your skewer, give your cake another 5 minutes. You do not want a completely clean skewer, crumbs mean the cake is done.