Step 1: Pulse 3 cups of Boo Berry cereal in a food processor until fine. Mix with melted butter and press into the bottom of a 9-inch springform pan. Chill in the freezer for 15 minutes.
Step 2: In a small saucepan, simmer blueberries, 2 tablespoons of sugar, and lemon juice over medium heat for 8-10 minutes until thickened. Strain and let cool completely.
Step 3: In a large bowl, beat the softened cream cheese and 1 cup of sugar until smooth. Stir in the vanilla and the 1/2 cup of finely powdered cereal.
Step 4: In a separate bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture until no streaks remain.
Step 5: Pour half of the filling into the crust. Drop small spoonfuls of the blueberry reduction on top. Add the remaining filling and more blueberry drops. Use a knife to swirl the colors together.
Step 6: Refrigerate for at least 6 hours, or preferably overnight, before serving. Garnish with extra cereal pieces.