pour your white cake batter into your pan/s and then drop by the spoonful a thicker type of caramel. I usually use the caramel that you can find either in the produce section (kind for dipping apples) or it is also sometimes together with the jams and peanut butters. Just make sure it is not a thin type. If it is a thicker type, you can mic it slightly then spoon it in and swirl with a knife like marbling and that's it. You can also drizzle some of that same caramel onto your borders depending on what you're doing.