Line the bottom of a 9-inch springform pan with parchment. Process the crispy pecans and 16 dates until the mixture holds together when pressed. Press evenly over the parchment, cover, and refrigerate.

If the blueberries are frozen, rinse them briefly with warm water and drain. Combine the blueberries, remaining 16 dates, and filtered water in a medium stainless-steel saucepan. Bring to a boil, then simmer about 20 minutes, stirring, until thick and jam-like and a spoon trail across the pan does not immediately close.

Let the compote cool completely before transferring it to the Ninja BN801 pitcher. Blend until smooth, stopping to scrape the pitcher if needed.

Whisk the chilled 24-hour cashew yogurt with the lemon juice. Drizzle in the melted room-temperature coconut oil while mixing continuously. Scrape the bowl and continue until smooth with no clear oil beads or streaks.

Spread exactly 2 1/2 cups of the plain cashew-yogurt mixture over the cold crust. Cover and freeze for 2 hours or until solid and no longer rippling when the pan is moved.

Whisk 3 tablespoons of the cooled blueberry compote into the remaining plain cashew-yogurt mixture. Cover and refrigerate while the first layer freezes.

Spread all remaining blueberry compote over the solid white layer, then spread the purple cashew-yogurt mixture evenly on top.

Cover and freeze for at least 4 additional hours, until the top is firm across the whole pan.

Release the springform ring. Thaw at room temperature about 1 hour before slicing; allow up to 2 hours if frozen solid. Slice into 16 servings. Serve within the following hour or refrigerate.