Preheat the oven to 425 degrees F. Lightly oil a baking sheet or coat with nonstick spray. Place the carrots in a single layer on the baking sheet. Add the olive oil, rosemary, thyme and season the carrots with salt and pepper. Gently toss to combine. Place the sheet tray in the oven and bake for 20-30 minutes, or until the carrots are tender. Add a splash of balsamic vinegar and serve.