Begin by heating 1 tablespoon of vegetable oil in a large skillet over medium heat. Once the oil shimmers, add the white parts of the green onion and diced onion. Sauté for about 2-3 minutes until the onions become fragrant and translucent.

Next, add the diced carrot, Spam (or your choice of protein), and optional mushrooms to the skillet. Stir everything together, cooking for about 3-4 minutes until the carrot softens and the Spam becomes slightly crisp.

Incorporate the day-old cooked rice into the skillet, breaking up any clumps as you stir. Pour in the soy sauce and ketchup, mixing well until everything is coated and heated through, around 2-3 minutes.

In a mixing bowl, whisk together the eggs, milk, and a pinch of salt until thoroughly combined. Heat the remaining tablespoon of oil in a non-stick skillet over medium-low heat. Pour in the egg mixture and gently scramble until the eggs are about 80% set.

Once the omelette is nearly cooked, carefully invert the bowl of rice onto a serving plate, forming a dome. Using a spatula, gently fold the omelette over the rice, securing it in place. Drizzle with ketchup and garnish with fresh parsley.