Cook frozen vegetables in boiling salted water for 2 minutes. Drain. Add green onion, 1/4 tsp (1 mL) Italian seasoning, garlic powder, salt and pepper. Set aside. In a bowl, beat together eggs, water, 1 tsp (2 mL) Italian seasoning, salt and pepper. Melt butter in a 10 inch (25 cm) non stick skillet over medium high heat. Pour 1/2 cup (125 mL) 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 2 more omelets. Place 3/4 cup (175 mL) cooked vegetable in the center of each omelet. Divide cheese among omelets. Fold 4 slices of each omelet over filling to create a square envelope. Invert onto plates, slice in half diagonally and serve hot or at room temperature.