Preheat the oven to 400°F and mill the wheat berries using your home mill.
100 g wheat berries
Melt the butter in a 12-inch skillet over medium-low heat. While the butter melts, chop the apples into ½-inch chunks. Add the apples to the skillet, then pour the honey and cinnamon over the top. Let everything simmer while you mix the batter.
3 tbsp butter, 3 apples, ¼ cup honey, 2 tsp cinnamon
Separate the eggs, putting the yolks in a large bowl and the whites in a medium bowl. Whisk the yolks with the milk and vanilla extract, then add the flour, baking powder, and salt directly on top. Mix until combined and let the batter rest while you whip the egg whites.
5 eggs, ½ cup milk, 1 tsp vanilla extract, 100 g wheat berries, 2 tsp baking powder, ¼ tsp salt
Whip egg whites to soft peaks, then gently fold into the rested batter until just combined. You don't want to overmix, but mix enough that the batter comes together for a uniform consistency.
5 eggs
Turn off the heat under the apples, spread them evenly in the skillet, then pour the batter over the top and smooth it out. Bake for 18–20 minutes, until puffed and set.