Julia Child smiling on the set of her WGBH cooking show, The French Chef
Julia Child's Foolproof Batter Tip To Prevent Sinking Fruit In Your Cakes
To keep fruit from sinking in cakes, Julia Child would pour some of the batter into a pan and put it on the stovetop over low to medium heat until it has a slightly congealed skin.
From there, you can add your fruit with the rest of the batter and bake. Child used this trick specifically when she made her berry clafoutis, but it is easily adaptable.
Fruit sinks in cakes due to their density and size. During baking, as the cake rises, gravity pulls down heavier fruit like cherries, blueberries, cranberries, apples, and strawberries.
Child's technique may seem intimidating, but once you perfect it, your fruit will be distributed throughout all your cakes much more evenly.