1Preheat an oven to 400 degrees F (200 degrees C). Grease 12 muffin cups, or line pan with paper muffin liners. Whisk together the egg, milk, and vanilla extract until smooth; set aside.
2Place the flour, sugar, baking powder, salt, and lemon verbena into a food processor. Pulse until the lemon verbena has been finely chopped. Add the butter, and pulse quickly until finely chopped. Pour the flour mixture into a mixing bowl, and stir in the blueberries. Pour in the milk mixture, and stir until just moistened. Fill the prepared muffin cups 3/4 full.
3Bake in the preheated oven until golden and the tops spring back when lightly pressed, about 20 minutes. Allow to cool before serving.