Preheat oven to 350 degrees F (175 degrees C). Grease a 12-cup muffin tin or line cups with paper liners.
Combine flour, baking powder, baking soda, and salt in a large bowl. Stir together 1/2 cup plus 2 tablespoons white sugar, unsweetened applesauce, yogurt, oil, vanilla sugar, and vanilla extract in a second bowl. Fold into flour mixture using a spatula, but do not over mix. Fold in blueberries.
Spoon batter into the prepared muffin cups, filling each 3/4 full. Sprinkle with brown sugar.
Bake in the preheated oven until tops spring back when lightly pressed, 18 to 22 minutes. Cool in the tin for 5 minutes. Transfer to a wire rack to cool completely.