Cook frozen vegetables in salted water 2 minutes. Drain.
Add green onion, 1/4 tsp (1ml) Italian seasoning, garlic powder, salt and pepper. Set aside.
Beat together eggs, water, 1/2 tsp (2ml) Italian seasoning, salt and pepper.
Over medium-high heat, melt butter in a 10-inch (25cm) nonstick skillet.
Pour 1/2 cup (125ml) egg mixture into skillet, tilting skillet to cover surface.
Cook 2 to 2 1/2 minutes or until set.
Slide omelet from skillet.
Repeat with remaining egg mixture to make 3 more omelets.
Place 1/2 cup (125ml) cooked vegetables in the center of each omelet.
Divide cheese between omelets.
Fold 4 sides of each omelet over filling creating a square envelope.
Invert onto plate, slice diagonally in half and serve hot or at room temperature.