Cheddar-Veggie Egg Envelopes

Heat small nonstick skillet on medium heat. Whisk first 3 ingredients until blended. Spray skillet with cooking spray. Add 1/3 cup eggs; tilt skillet to evenly cover bottom with eggs. Cover; cook 1 to 2 min. or until eggs are set. Slide omelette onto plate. Repeat with remaining eggs to make a total of 4 omelettes. Cover to keep warm until ready to use.

Add spinach, mushrooms and tomatoes to skillet; cover. Cook on medium-low heat 5 min. or just until spinach is wilted.

Fold each omelette in half, then in half again to form triangle. Serve topped with vegetable mixture and cheese.