Preheat the oven to 350°. In a pie plate, toss the brioche with half the butter and bake for 5 minutes, or until golden. Transfer to a bowl, add the sugar and cinnamon and toss well.
Cut 1/2 inch from the tops of the apples. Using a melon baller, scoop out the seeds and cores. Spoon the bread filling into the apples and drizzle with the remaining butter and the Calvados. Bake the apples for about 40 minutes, or until tender; cover them with foil if the brioche browns too quickly.