1. Combine flour with sugar and baking powder in a large bowl. Cut in butter until it is in tiny pieces. Remove 3/4 cup (180 mL) of this mixture to a small bowl. Stir in cinnamon. Reserve.
2. Combine milk with eggs and vanilla and add to flour mixture in the large bowl. Stir just until moistened. Stir blueberries in gently.
3. Spoon batter into 12 large buttered or paper-lined muffin cups. Sprinkle each with the reserved cinnamon/crumb mixture.
4. Bake 30 to 35 min in a preheated 350°F (180°C) oven. Cool 5 to 10 min before removing from pan.
5. Serve at room temperature
These cake-like muffins are sure to become a favorite family treat. If you are using frozen blueberries, do not defrost before stirring into the batter.