1. Preheat the oven to 425F/220C. Line a baking tray with aluminium foil.
2. Cut away the ends and tips of each carrot. You can peel the carrots if necessary.
3. Cut the carrot crosswise into halves. Then cut each half lengthwise. Cut each half into halves again, lengthwise. Repeat this with the other carrots.
4. Combine the carrot sticks, olive oil, rosemary and salt and pepper into a bowl. Stir with a rubber spatula until the carrot sticks are coated evenly with all the ingredients.
5. Place the carrots onto a foil-lined baking tray, scraping out any herbs clinging to the sides of the bowl.
6. Spread the sticks out and bake until the carrots are tender, for about 20 minutes.
7. Take the pan from the oven. Serve the carrot fries hot, or at room temperature.