In a bowl, toss the mushrooms with olive oil, minced garlic, thyme, salt, and pepper.
Spread the mushrooms on a baking sheet in a single layer.
Roast for 15-20 minutes, stirring halfway through, until golden and tender.
While the mushrooms roast, heat balsamic vinegar in a small saucepan over medium heat. Bring to a simmer and cook until it reduces by half (about 5 minutes). Add honey for sweetness, if desired.
Once the mushrooms are done, drizzle the balsamic reduction over them and serve.
Notes
Balsamic reduction can be made ahead and stored in the fridge for up to a week.
Use any variety of mushrooms for a different texture or flavor.