Knead the flour, butter, egg yolk, diabetic sweetness and 1 tablespoon of cold water into a smooth short pastry. Cover and let rest for 20-30 minutes. Roll out on a floured work surface (23 cm Ø) and line a greased springform pan (20 cm Ø) with it and press the dough to the edge. Prick the base several times with a fork and put in a cool place. Wash, halve and core the pear. Peel one half and cut into small pieces.
Separate the eggs. Cream egg yolk, diabetic sweetness and butter. Cut the vanilla pod lengthwise and scrape out the pulp. Mix the vanilla pulp, lemon zest and quark with the egg mixture. Sift the cornflour over the egg mixture and stir in. Beat the egg white until stiff and fold into the quark mixture with the pear pieces. Spread on the short pastry base and bake in the preheated oven (electric: 175 °C / gas: level 2) for approx. 50 minutes. After approx. 25 minutes switch on (electric oven: 200°C / gas: level 3) and finish baking. In the meantime, cut the remaining pear half into thin slices. Bring lemon juice, sweetener and 2-3 tablespoons of water to the boil in a saucepan. Steam the pear slices for approx. 2 minutes and drain. 5-10 minutes before the end of the baking time, spread them fan-shaped on the cake and bake with it.
Beat the egg white until stiff and fold into the quark mixture with the pear pieces. Spread on the short pastry base and bake in the preheated oven (electric: 175 °C / gas: level 2) for approx. 50 minutes. After approx. 25 minutes switch on (electric oven: 200°C / gas: level 3) and finish baking. In the meantime, cut the remaining pear half into thin slices. Bring lemon juice, sweetener and 2-3 tablespoons of water to the boil in a saucepan. Steam the pear slices for approx. 2 minutes and drain. 5-10 minutes before the end of the baking time, spread them fan-shaped on the cake and bake with it. Let the cake cool down, remove from the tin and serve decorated with lemon balm. Makes 8 pieces