Have you ever had fresh or dried fruit sink to the bottom of a cake or loaf? Don’t worry, it’s a common problem and generally happens when the cake batter isn’t heavy or thick enough to hold the weight of the fruit as it bakes.
The best way to avoid sinking fruit is to toss the fruit in a couple of tablespoons of the flour (just use some from the measured amount for the recipe) to coat it lightly. Once added to the cake mixture the flour coating will thicken the batter immediately surrounding the fruit and help suspend the fruit.
Keep in mind though, large pieces of fruit like whole raisins will be far too heavy even if coated with flour and you will need to cut these into smaller portions to have success. This will be the same with large chunks of chocolate and are also best cut into smaller pieces.