Place 1/3 cup freeze-dried blueberries in a zip-top bag and crush them with a rolling pin until finely powdered, then set aside.

In a small saucepan over low heat, add the white chocolate chips, softened cream cheese, and unsalted butter. Stir constantly until fully melted and smooth.

Remove the saucepan from the heat and stir in the lemon juice, lemon zest, vanilla bean paste, and salt until evenly combined.

Place the Rice Chex cereal in a large mixing bowl. Pour the warm cheesecake mixture over the cereal and gently fold with a spatula until all pieces are evenly coated.

Add the 3/4 cup whole freeze-dried blueberries to the coated cereal and gently fold to distribute them evenly.

Transfer the coated cereal mixture to a gallon-size zip-top bag. Add the powdered sugar and the crushed freeze-dried blueberry powder, seal the bag, and shake until all pieces are dry and evenly coated.

Spread the puppy chow in a single layer on a baking sheet and let cool at room temperature for 10 minutes before serving or storing.