1. Heat oven to 400F.
2. Line 12 medium muffin cups, 2 1/2x1 1/2 inches, with paper baking cups, or grease bottoms only of muffin cups.
3. Mix all ingredients except blueberries just until flour is moistened (batter will be lumpy). Fold in blueberries.
4. Divide batter evenly among muffin cups.
5. Bake 20 to 25 minutes or until golden brown.
6. Immediately remove from pan.
7. High Altitude (3500-6500 ft): Heat oven to 425F. Decrease brown sugar to 1/3 cup. Bake about 20 minutes.