In a large bowl, combine flour, sugar, baking powder and salt. Add margarine until mixture resembles breadcrumbs.

In another bowl, using a metal fork, combine egg, milk, lemon juice and vanilla sugar and beat slightly. Fold into crumb mixture until smooth (do not over mix!) Fold in blueberries.

Spoon batter into a greased muffin tin.

In a small bowl, combine all crumb topping ingredients and sprinkle over each muffin.

Bake uncovered at 350 degrees Fahrenheit for 30-35 minutes or until a toothpick comes out clean when inserted.

Preheat oven to 350 degrees Fahrenheit.