01 - Heat vegetable oil in a large skillet over medium heat. Add diced chicken and sauté until cooked through and no longer pink, approximately 4 to 5 minutes.
02 - Add chopped onion and diced carrot to the skillet. Cook until softened, about 3 minutes. Stir in frozen peas and cook for an additional minute.
03 - Add cooked rice to the skillet, breaking apart any clumps with a spatula or rice paddle. Toss thoroughly to combine with the vegetables and chicken.
04 - Pour in ketchup and soy sauce, stirring until the rice is evenly coated and heated through. Season with salt and pepper to taste. Remove from heat and divide the rice into two oval-shaped mounds on serving plates.
05 - In a mixing bowl, whisk together the eggs, milk, and a pinch of salt until fully blended and slightly frothy.
06 - Melt 1 teaspoon of butter in a nonstick frying pan over medium-low heat. Pour in half of the egg mixture, tilting the pan to spread it evenly. Cook while gently stirring the edges until they are set but the center remains soft and slightly runny.
07 - Carefully slide the omelette out of the pan and drape it over one of the rice mounds, gently shaping it with the spatula to cover the rice. Repeat the omelette cooking and assembly process with the remaining butter, egg mixture, and second rice mound.
08 - Drizzle extra ketchup over each assembled omurice. Sprinkle with chopped parsley if desired. Serve immediately while warm.