This was in Cooking Light -- I made a few changes mostly to bake them in a large muffin tin and to use buttermilk.

Blueberry Cinnamon-Burst Muffins

12 large muffins

Preheat oven to 400 degrees

6 Tbsp. AP flour
6 Tbsp. sugar
1 1/2 Tbsp. cinnamon
4 1/2 Tbsp. chilled butter

Combine and cut in butter until mixture resembles coarse meal. Cover and chill 30 minutes.

1 1/2 cup sugar
1/2 cup butter, softened (1 stick)
3 large eggs
3 3/4 cups AP flour
4 1/2 tsp. baking powder
3/4 tsp. baking soda
3/4 tsp. salt
1 1/2 cups buttermilk
2 1/4 cups blueberries

Cream butter and sugar. Add eggs, 1 at a time, beating well after each addition. Combine dry ingredients. 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).

Spoon batter into muffin cups coated with cooking spray. Bake at 400 degrees for 20-25 minutes. Cool in pans 5 minutes. Remove muffins from pans, place on a wire rack.