Peel and mash the banana. Mix the egg, sugar, vanilla sugar, quark, oil, banana, orange zest and orange juice. Mix the flour and baking powder and quickly mix into the batter.
Line a muffin tin with paper cups. Pour the batter into the muffin tin. Bake for about 30-35 minutes at 200°C (approximately 400°F). Serve dusted with powdered sugar.