Preheat your oven to 180°C (350°F). Lightly grease your oven-safe skillet or casserole dish with a little oil or butter.
Chop the onion, carrots, and bell pepper into small, even pieces to ensure they cook uniformly and look colorful in the final dish.
Heat the vegetable oil in the skillet over medium heat until it shimmers and you can hear a gentle sizzle. Add the diced onion and minced garlic, sautéing until fragrant and translucent, about 2-3 minutes. The smell will fill your kitchen with a warm aroma.
Add the chopped carrots and bell peppers to the skillet. Cook, stirring occasionally, until the vegetables start to soften and develop a slight caramelization, about 8-10 minutes. They should be tender but still vibrant in color.
Stir in the cooked rice, breaking up any clumps with your spoon. Mix well to combine all the ingredients evenly. Let it cook for another 2-3 minutes, allowing the rice to heat through and absorb some flavors.
Pour in the vegetable broth or water, stirring gently to moisten the mixture. Season with salt and pepper, then let everything simmer for a few minutes until the liquid slightly reduces and the flavors meld together.
Sprinkle the shredded cheese evenly over the top of the mixture. Cover the skillet loosely with foil or a lid to help the cheese melt and the casserole heat evenly.
Transfer the skillet to the preheated oven and bake for 20-25 minutes, until the cheese is bubbly and golden. The dish will smell warm and inviting, with a slight crust forming on top.
Carefully remove the casserole from the oven using oven mitts. Let it rest for about 5 minutes—this helps everything set and makes serving easier.
Sprinkle freshly chopped herbs like parsley or basil if desired for a burst of freshness. Then, scoop out portions and serve hot, enjoying the comforting textures and vibrant colors.
