Pro Tips: For the perfect gooey texture, do not overbake – a toothpick should come out with moist crumbs. The batter will be thick – that's exactly right. Feel free to customize the mix-ins based on what you have. This cake is best served warm with a scoop of vanilla ice cream. Leftovers can be stored at room temperature for up to 3 days or frozen for up to 3 months.