For a quicker method, place walnuts in a container with water and microwave until the water boils. Once cooled, peel them with your hands or a nutcracker.
Traditional Oven Approach
Another simple way is using your oven. Preheat it to 180°C, place walnuts on a baking sheet, and let them sit for at least 5 minutes. The shells become slightly hard, making them easier to peel.