Butter tart pan.
Roll out puff pastry until slightly larger than the tart pan. Line pan with it, making an edge all around.
Rinse and dry apricot, halve and pit. Mix with lemon juice and honey.
Whisk quark with egg, cornstarch, vanilla sugar and liqueur. Spread mixture on pastry and smooth. Sprinkle with almonds and arrange apricots on top decoratively. Bake in preheated pven at 200°C (approximately 400°F) for about 45 minutes or until golden brown.
Melt remaining butter and brush apricots and top of pastry during the last 10 minutes of baking. Sprinkle with powdered sugar.
Cool and garnish with lavender. Serve.