Roughly chop chocolate. Combine flour and baking powder. Grease springform pan and dust with flour. Preheat oven to 150°C/300°F (convection).
Bring cream to a boil, then remove pot from the stove. Add chocolate and stir well until melted. Set aside.
Whisk butter, sugar, and salt until creamy. Add eggs individually and continue to whisk. Next, add the chocolate-cream and flour mixtures, and stir well to combine.
Wash and peel apples. Cut to personal preference—thin slices, for example. Fold into cake batter. Transfer batter to springform pan. Bake at 150°C/300°F (convection) for approx. 1 h. As baking time may vary from oven to oven, make sure you test cake for doneness. Insert wooden skewer into cake. If skewer comes out clean, cake is done. I serve it with caramel sauce and brittle.