Add the oil in a large pot or casserole over medium heat for 1-2 minutes. Add the onions and sauté until translucent. Add the garlic and sauté for half a minute until fragrant.
Increase the heat to max and add to the pot the mushrooms, thyme and Worcestershire sauce and let sizzle and brown on one side before tossing. Cook for about 5 minutes tossing frequently. Last minute season with half of the salt and pepper and sprinkle with the mushroom powder.
Add the rice and the broth and stir. Bring to a boil, lower the heat with the lid on and simmer for 16-18 minutes. 1 minute before turning off the heat add the butter, season with the remaining salt and pepper and stir for the butter to melt. Turn off the heat, open the lid, cover the pot with a towel, place back the lid and let stand for about 5 minutes to concentrate all the liquids into the rice.
Serve and optionally sprinkle with finely chopped chives or parsley.