Chopping chocolate. Cut butter into pieces. Melt the chocolate and butter in a wide pot at low heat.
Beat the eggs, brown sugar and salt in a bowl with the whisk of the hand mixer for 3-4 minutes until creamy. Remove the chocolate and butter mixture from the heat and immediately pour into the egg mixture and stir in.
Mix flour, cocoa and baking powder. Quickly fold into the chocolate-egg mixture.
Spread the dough into a greased baking tray (33 x 37 cm). Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 25 minutes. Remove and let cool on a cake rack.
Soak gelatine in cold water. Mix apple sauce with cinnamon. Whip the cream until stiff, while pouring in 1 sachet of vanillin sugar. Mix quark, lemon juice and sugar with a whisk until smooth.
Gradually fold in the cream. Squeeze the gelatine, dissolve and stir in 4 tbsp. of the quark cream, stir into the remaining quark cream. Fold in apple puree in streaks, spread the mixture on the brownie base.
Place the butter biscuits on top and chill for at least 1 1/2 hours.
Cut apple brownies into pieces and arrange on a plate. Use a spoon to spread the caramel spread on the pieces.