HEAT oven to 375ºF.
PREPARE muffin batter as directed on package; spoon into 24 mini muffin pan cups sprayed with cooking spray.
PRESS 1 each VELVEETA cube and hot dog slice into batter in center of each muffin cup.
BAKE 10 to 12 min. or until golden brown. Cool 5 min. before removing from pans. Serve warm with mustard.