Combine flour with sugar and baking powder in a large bowl. Cut in butter until it is in tiny pieces. Put 3/4 cup of this mixture to a small bowl. Stir in cinnamon and put aside. Combine milk with eggs and vanilla and add to flour mixture in large bowl. Stir just until moistened. Stir in blueberries. Spoon batter into 12 large butter or paper-lined muffin cups. Sprinkle each with the cinnamon crumble mixture. Bake 30 to 35 min. in preheated 350 degree oven. Cool 5 to 10 min. before removing from pan. Note: If using frozen blueberries, do not defrost before stirring into the batter. Yield: 12 large muffins.