HEAT oven to 375ºF.
MIX first 6 ingredients in large bowl. Stir in vegetables. Whisk egg, milk and dressing until well blended. Add to flour mixture; stir just until moistened. (Batter will be lumpy.) Stir in trail mix.
SPOON into 12 paper-lined muffin cups.
BAKE 20 min. or until golden brown.