Cut the bagels crosswise. Wash lemon balm and pluck off a few tips for decoration.
Mix the cream cheese with the maple syrup until it is creamy. In a second bowl, crush half of the blueberries with a fork and fold into the cream cheese together with the whole berries. Whip the cream until it is half stiff, then stir in the vanilla sugar, whip the cream until it is very stiff.
Brush the bagel halves with the cream cheese, pour some whipped cream over them and garnish with blueberries and lemon balm.