Preheat oven to 400°. Spray two 12-cup mini-muffin tins well with cooking oil spray.
Place broccoli in a 2 cup glass measure and microwave, uncovered, for 2 minutes on high.
Meanwhile, break the egg into a 2Qt. bowl and beat with a whisk or fork to break it up. Add the milk and beat well t blend. Stir in the cheese. Stir in the muffin mix just until the dry ingredients are moistened.
Remove the broccoli from the microwave and press out any excess water. Finely chop the broccoli and add it to the batter. Using a tablespoons measure or a cookie-dough scoop, fill the prepared muffin cups about 2/3 full. When the batter is used up, fill the unused cups halfway with water, to prevent burning.
Bake in the middle of the oven until the muffins just begin to brown around the edges and spring back when touched, 12 to 14 minutes. Serve warm.(Makes about 20 mini-muffins)
*Leftovers should be wrapped in plastic or aluminum foil and refrigerated, good for up to 3 days.
Variation: Use about to 1 cup of grated carrot instead of broccoli.