01 -
Line a 20 cm square baking pan with parchment paper, leaving an overhang to aid removal.
02 -
Combine graham cracker crumbs, melted butter, and sugar in a mixing bowl. Press the mixture firmly and evenly into the bottom of the prepared pan to create a solid base.
03 -
In a microwave-safe bowl, combine 150 g mini marshmallows and 30 g butter. Microwave in 20-second bursts, stirring between each, until fully melted and smooth. Spread the marshmallow mixture evenly over the graham cracker base and allow to cool for 5 minutes.
04 -
In a separate microwave-safe bowl, combine semisweet chocolate chips and heavy cream. Microwave in 20-second intervals, stirring until melted and silky. Pour over the marshmallow layer and smooth with a spatula.
05 -
Immediately scatter remaining mini marshmallows, graham cracker pieces, and chocolate chips (if using) over the chocolate layer. Gently press toppings into the surface.
06 -
Refrigerate for at least 1 hour, or until fully set. Use the parchment overhang to lift from the pan. Cut into bars and serve.