Mix sugar and butter until fluffy. Beat in egg. Stir in flour mix with baking powder and salt alternately with milk, beginning and ending with the flour.
Stir in the vanilla and beat well. Gently fold in blueberries.
Spoon batter into greased muffin pads filling cups 2/3 full.
Mix sugar, cinnamon, flour, and butter until crumbly. Sprinkle crumbs over muffins.
Bake in preheated moderate oven 375 F or 190 C for 20 to 25 minutes or until golden brown serve warm.