Why does this happen?
When it comes to small fruits and berries, chocolate chips and even dried fruits such as raisins, they tend to bring added weight and the batter may be too thin to hold them up as your dessert bakes.
How to prevent it
To ensure your add-ins are evenly distributed in your dessert, all you need to do is toss them lightly in flour (or cornstarch) before folding them into the batter. The batter now has something to adhere to and the fruit will be suspended in place during the baking process.
If your fruit is too wet (like diced strawberries, for example), be sure to blot them with a paper towel to remove excess moisture before coating. This will keep the colour from bleeding into the batter. And if you’re using frozen fruits, keep them in the freezer until you’re ready to coat and add them to your recipe.
Be sure to try this hack with the following recipes: