1. Preheat oven to 400.
2. Lightly spoon 1/4 cup flour into a measuring cup; level with a knife. Combine 1/4 cup flour, 1/4 cup sugar, and cinnamon in a medium bowl, and cut in 3 tablespoons butter with a pastry blender or 2 knives until mixture resembles coarse meal. Cover and chill 30 minutes.
3. Place 1 cup sugar and 1/3 cup butter in a bowl; beat with a mixer at high speed 1 minute or until combined. Add eggs, 1 at a time, beating well after each addition. Lightly spoon 2 1/2 cups flour into dry measuring cups, level with a knife. Combine 2 1/2 cups flour, baking powder, and salt, stirring with a whisk. Add flour mixture and milk alternately to butter mixture, beginning and ending with flour mixture. Fold in blueberries and cinnamon mixture (batter will be thick).
4. Spoon batter into 18 muffin cups coated with cooking spray. Bake at 400 for 18 minutes or until muffins spring back when touched lightly in center. Cool in pans 5 minutes on a wire rack. Remove muffins from pans; place on a wire rack.
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