COMBINE cream cheese and onion in medium bowl with wooden spoon. Stir in spinach, pepperoni and flour. Mix well. Stir in egg until smooth.
POUR into 24 greased mini muffin cups. Remove excess oil from sundried tomato pieces using paper towel. Top each frittata with a piece of sundried tomato . Bake at 350°F for 15-18 minutes, or until set and golden. Serve warm or cold.