Place the rice into a fairly large pot with about 4 cups of water. Add the salt and turn the heat on high. Boil the rice until it is almost done, about 40 minutes.

Meanwhile, chop the onions, garlic and celery. Heat 1 tablespoon of olive oil or grapeseed oil in a sauté pan. Sauté the vegetables in the hot oil until they are soft. Add the sliced mushroom and cook until the mushrooms have lost their moisture and started to brown. Grate the carrot and set aside.

Preheat the oven to 375ºF.

About 2 minutes before the rice is ready, add the chopped broccoli to the pot with the rice and water. Cook the broccoli for about 2 minutes. Drain the rice and broccoli and return the mixture to the pot. Add the garlic, onion, celery and mushroom mixture to the rice and broccoli. Add the frozen peas (still frozen is fine), the grated carrot and the green onions. Add the thyme. Mix all together and pour into a baking dish. Pour the chicken stock over the mixture and sprinkle the top with cheddar cheese.

Bake the rice casserole at 375º for about 20 to 25 minutes, until everything is heated through and the cheese is melted. I cover the casserole for the first 15 to 20 minutes, then leave it off for about 5 minutes for the cheese to melt.