Heat oven to 400°F. Spray bottoms only of 12 regular-size muffin cups with cooking spray, or line with paper baking cups. Spray bottoms only of paper baking cups with cooking spray. In large resealable plastic food-storage bag, coarsely crush cereal with rolling pin or meat mallet to measure 1 3/4 cups.
In large bowl, mix cereal, flour, brown sugar, baking soda and salt. In medium bowl, beat buttermilk, oil, vanilla and egg until blended. Add buttermilk mixture to flour mixture; stir just until dry ingredients are moistened. Stir in dates. Spoon batter into muffin cups. Sprinkle with coarse sugar.
Bake 18 to 20 minutes or until light golden brown. Remove from pan to cooling rack. Serve warm or cool.