Cook the onions and garlic cloves until browned, about 5-7 minutes.
Next, add in the mushrooms and cook over medium-high heat for 10-12 minutes or until lightly browned.
Pour in the rice and cook over medium heat for 1 to 2 minutes to toast the rice.
Add 1 cup of chicken stock at a time to the mixture while continuing to stir the rice until it has absorbed all the liquid before adding in the next cup. Repeat until the rice is cooked.
Finish by stirring in the peas, cream, cheese, thyme, salt, and pepper. Serve.