Step 1

Heat the oven to 350 degrees, with a rack in the center position. Generously butter an 8-inch springform pan.

Step 2

In a small bowl, whisk together the whole wheat and all-purpose flours with the baking powder and salt.

Step 3

Place the eggs in a medium bowl, and beat them with a whisk till they’re foamy. Add the sugar and whisk till blended, then whisk in the Calvados and vanilla. Whisk in half the flour mixture, followed by half the melted butter, then the rest of the flour mixture, followed by the rest of the melted butter. Give it a gentle stir to make sure everything is well combined into a smooth, thick batter.

Step 4

Fold in the apples, coating them evenly with the batter. Turn the batter into the prepared pan, smoothing the top a bit.

Step 5

Place the springform pan on a parchment-lined sheet pan and bake for 50 to 60 minutes, or until the top of the cake is golden brown and a knife inserted deep into the center comes out clean. Set the springform pan on a rack to rest for 5 minutes.

Step 6

Run a thin knife around the edges of the cake, release the spring on the pan. Check to see that no apples are stuck to the sides, and then remove the sides of the pan. Allow the cake to cool until it is just slightly warm or at room temperature.