Preheat the oven to 350F, and spray a regular 12 hole muffin pan with some nonstick cooking spray.
In a bowl, whisk together the egg, egg whites, and brown sugar until the mixture is light and fluffy.
Mix in the apple sauce, lemon juice, milk and vanilla.
Stir in the all purpose flour, lemon zest, baking powder, and baking soda then mix it all together well.
Gently fold in the blueberries. Divide the batter among the 12 muffin cups.
In a small bowl, mix the crumble flour and sugar together. Add in the melted margarine, and use a fork to it to form a crumble. Sprinkle the crumble over the 12 muffins.
Bake the muffins in the oven for 24 minutes.
Let them cool before removing from the muffin tin. Use a knife around the edges for the best results.