Evenly coat 10-inch omelet pan or skillet with ovenproof handle with spray. Add broccoli, carrot and water. Cover and cook over medium-high heat until carrot is crisp-tender, about 5 to 10 minutes. (Uncover and stir occasionally, if necessary, to break apart frozen broccoli.) Drain well. Return vegetables to pan. Set aside.
In large bowl, beat together eggs, cheese, milk, onion, mustard, salt, if desired and pepper until well blended. Pour over reserved vegetables. Cover and cook over medium heat until eggs are almost set, about 8 to 10 minutes.
Uncover and broil about 6 inches from heat until eggs are completely set in center, about 2 to 3 minutes OR let stand, covered, until eggs are completely set in center, about 8 to 10 minutes. Cut into wedges and serve from pan or either slide from pan or invert onto serving platter.
* To make handle ovenproof wrap completely with aluminum foil.