Preheat oven to 275 degrees Fahrenheit (135 degrees Celsius). Line a baking sheet with parchment paper.

Spread the Rice Krispies and crushed cornflakes on the prepared baking sheet. Bake for 10–15 minutes. Allow to cool completely before using.

Melt margarine, marshmallow cream, and peanut butter in a large nonstick pot over low heat, stirring until smooth. Remove from heat. Stir in vanilla extract.

Pour the cereal into the mixture and fold gently to coat. Allow to cool for two to three minutes.

Using wet hands, form ping-pong-size balls, forming a deep indentation in each. Pour a little popping candy into each indentation and reshape to form a ball.

Place the chocolate in a microwave-safe bowl and heat in 20-second intervals, until melted. Drizzle the balls with chocolate and sprinkle with additional popping candy. Allow to cool.

Store uncovered to retain its crispy texture.