In a medium saucepan over low-medium heat, combine the soft light brown sugar, golden syrup, and creamy peanut butter. Stir continuously for about 3-4 minutes until the mixture has melted together and become slightly softened.

Transfer the melted mixture to a large mixing bowl, and add in the rice crispies. Use a spatula to gently fold the cereal into the mixture.

Line a muffin tray with cupcake cases. Divide the crispy mixture evenly among the cases, pressing down firmly to create a solid base.

In a microwave-safe bowl, melt the chocolate in 30-second increments, stirring in between until fully melted and smooth.

Drizzle the chocolate-peanut butter mixture over each pressed rice crispy base, covering them generously.

Before the chocolate sets, sprinkle a pinch of flaky sea salt on top of each cup.

Let the cups sit at room temperature for about 30 minutes or refrigerate them to speed up the setting process.