Preheat the oven to 400 degrees. Coat a baking sheet with cooking spray.
Place the mushrooms in the center of the baking sheet then drizzle with olive oil and add fresh thyme leaves, then season with sea salt and freshly cracked pepper, to taste; toss to coat evenly.
Spread the mushrooms out in one layer on the baking sheet and top with a sprig of fresh thyme.
Place into the oven and roast for 10 minutes then flip them with a spatula, and cook for another 10 minutes, or until golden brown.
Place the minced garlic into the melted butter; set aside.
Remove the mushrooms from the oven and drizzle the melted garlic butter on top then place back into the oven for 3-5 minutes.
Remove from the oven and squeeze juice and zest from 1/2 a lemon over the mushrooms and top with a few more fresh thyme leaves; toss to coat evenly.
Place into a serving bowl with lemon wedges on the side. Serve immediately. Enjoy.