Preheat oven to 350 degrees. Lightly spray glass pie pan with non-stick spray and set aside.
Place cereal in food processor and pulse until it is fine. There will still be some nutty bits. Add thawed apple juice and pulse until combined. Use a spatula to scrape sides of food processor and ensure that all of the cereal is moistened.
Place mixture in bottom of pie pan and pat out until the bottom is covered as well as half way up the sides. Bake for 5 minutes.
Meanwhile, combine condensed milk, eggs, lemon juice and zest with whisk until well blended. Pour into prepared pie crust and bake for 15 minutes.
Allow to cool completely and then refrigerate for a couple of hours. Best served cold.
Garnish with whipped cream, if desired.
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Notes
You can make your own concentrate by boiling one cup of apple juice over medium-high heat until it cooks down to ¼ cup. Allow it to cool before using it in this recipe.