Heat the olive oil in a large skillet over medium heat.
Add the minced garlic and sauté for about 30 seconds until fragrant.
Add the sliced mushrooms to the skillet and cook for 5-7 minutes, stirring occasionally, until they are browned and tender.
Stir in the cauliflower florets, thyme, salt, black pepper, and red pepper flakes (if using).
Cover the skillet and cook for an additional 8-10 minutes, stirring occasionally, until the cauliflower is tender but still crisp.
Remove from heat and garnish with fresh parsley before serving.