Preheat oven to 400 degrees. Clean mushrooms with a mushroom brush or a damp paper towel and slice into pieces.
Line a baking pan with foil and spray lightly with non-stick food spray. In a large bowl, combine the mushrooms with the olive oil, sea salt, pepper, chopped garlic and thyme. Place mushrooms in an even layer on the prepared pan.
Place in the preheated oven and roast until mushrooms turn light brown and become slightly crisp around the edges, approximately 12- 14 minutes.