Slice the carrots in half lengthwise. Place them on a rimmed baking sheet. Drizzle over 2 tablespoons of the olive oil, sprinkle them with salt and pepper, and toss the carrots so they are well coated with the oil.
Spread them out in a single layer. Roast for about 20 minutes until they are tender but not soft and browned along the edges.
Notes
If you have the oven set at 400 degrees or 450 degrees for another dish, that’s fine. Just check the carrots a little earlier at a higher temperature, and be prepared to let them cook for a few extra minutes at a lower temperature. Watch that they don’t brown too much at a higher temperature.
If your carrots are young and the outside looks nice and fresh, with just a paper-thin skin and no cloudiness or bristly hairs, you might be able to skip the peeling and just give them a good scrub.
For skinny carrots, less than ½ inch wide at the top, you don't need to cut them in half lengthwise. Just leave them whole.
Line the baking sheet with foil or parchment first, if you like, for easier cleanup.