Wash carrots thoroughly and cut off tops– no need to peel them. Dry with a paper towel or clean dish towel. For even cooking, halve or even quarter the thicker carrots so each carrot is roughly the same thickness.
Place in single layer on parchment-lined baking sheet and drizzle with olive oil and balsamic vinegar. Sprinkle on garlic, thyme, salt, and pepper.
Bake at 375 degrees for 40-50 minutes, depending on thickness, until tender and starting to slightly crisp. Sprinkle with fresh parsley, if using, and serve immediately.