1 Line a 24 cm (approximately 9 1/2 inch) springform pan with parchment paper. Drain sour cherries well and reserve juice.
2 For the dough: Combine butter with sugar, egg, egg yolk and salt until fluffy. Stir in flour, baking powder and milk. Add chopped chocolate chips and mix.
3 Pour batter into pan and bake for about 20 minutes in a preheated oven at 175°C (gas mark 2) (approximately 350°F). Remove from oven, turn out onto a wire rack, remove parchment paper and leave to cool.
4 For the filling: Heat sour cherry jam, strain through a sieve and spread onto crust and spread evenly. Close edge of springform pan around crust.
5 Soak red and 2 sheets of clear Gelatine in cold water and then dissolve while dripping wet on low heat. Pour 200 ml (approximately 7/8 cup) reserved cherry juice and stir into dissolved Gelatin. Combine cherries with 4 tablespoons powdered sugar, mix with juice and leave to set in refrigerator.
6 Pour cherry Gelatin evenly onto crust, smooth and refrigerate.
7 Beat 250 grams (approximately 9 ounces) cream with 2 tablespoons of powdered sugar and 1/2 package vanilla sugar until stiff. Stir in yogurt and 80 ml (approximately 1/3 cup) Advocaat. Melt chocolate in a bowl set over (not in) a pot of hot water, mix with 2 tablespoons of cream and fold into remaining cream.
8 Soak 4 remaining sheets of clear Gelatin in cold water and dissolve over low heat. Mix liquid Gelatin with 2 tablespoons of cream and stir into rest of the mixture. Spread onto cherry layer and smooth out. Refrigerate for 2 hours.
9 Add remaining vanilla sugar to 150 grams (approximately 5 1/4 ounces) cream until stiff and spread evenly onto cake. Press into the cream with a spoon, pour in remaining Advocaat and sprinkle with pistachios and serve.