Heat oven to 350 degrees F. Spray bottom only of 9x5-inch loaf pan with cooking spray.
In medium bowl, stir muffin mix, water, oil and eggs just until blended (batter may be lumpy). Gently stir in blueberries. Spread in pan. Sprinkle sugar crystals over batter.
Bake 50 to 60 minutes or until toothpick inserted in center comes out clean. Cool 15 minutes. Remove from pan to cooling rack. Cool completely, about 1 hour. Wrap tightly and store in refrigerator.