COMBINE flour, sugar and baking powder in large bowl. Chop 12 cookies.
WHISK egg with milk, butter and vanilla in medium bowl until blended. Stir in bananas. Add to dry ingredients stir just until moistened. Stir in chopped cookies.
SPLIT remaining cookies. Scrape creme off cookie halves into small microwaveable bowl; reserve creme for later use. Chop plain cookie halves.
SPOON muffin batter into 12 paper-lined muffin pan cups; sprinkle with chopped (plain) cookie halves. Gently press cookie pieces into top of batter to secure.
BAKE 15 to 20 min. or until toothpick inserted into centers of muffins comes out clean. Cool 5 min. Remove muffins from pan to wire rack; cool 15 min.
MICROWAVE reserved creme on HIGH 15 to 30 sec. or until melted; stir. Drizzle over muffins. Serve warm.