Prepare the Apples: Peel, core, and chop the apples into small pieces. Place the apples in a large pot and cook them over medium heat until they break down and soften into a puree. Use a blender or food processor to puree the cooked apples until smooth.
Make the Candy Base: In the same pot, combine the apple puree with sugar, corn syrup, and pectin. Stir the mixture continuously while cooking over medium heat, making sure everything is dissolved. Allow the mixture to thicken to a gel-like consistency, which should take around 20-30 minutes.
Add the Walnuts: Once the mixture has thickened, remove it from the heat and fold in the toasted walnuts. Ensure the nuts are evenly distributed throughout the mixture.
Set the Mixture: Pour the mixture into a parchment-lined 9x9-inch pan. Spread it evenly with a spatula, then let it cool to room temperature. Afterward, refrigerate for several hours or overnight to allow the candy to set completely.
Cut and Coat: Once the mixture is firm and set, remove it from the pan and cut it into small cubes. Coat each piece generously with powdered sugar to prevent sticking and give it a soft, sweet finish.