250g packet Marie biscuits
150g unsalted butter, melted
24 (150g) white marshmallows
200g block dark chocolate, chopped
150g unsalted butter, chopped
2/3 cup caster sugar
2 eggs, lightly beaten
1⁄2 cup plain flour
2 tblsps cocoa powder
Grease an 18cm x 28cm rectangular slice pan. Line base and sides with baking paper, extending paper 4cm above pan edges.
Process biscuits in a food processor until finely crushed. Add butter and process until combined. Press over base of prepared pan. Refrigerate while making filling.
To make filling, combine chocolate and butter in a heatproof bowl. Sit bowl over a saucepan of simmering water. Stir until melted and smooth. Remove bowl from heat. Stand 10 minutes to cool.
Stir sugar into chocolate mixture. Add eggs, sifted flour and cocoa. Stir until combined. Pour over base.
Cook in a moderately slow oven (160C) for 25 minutes. Remove from oven. Carefully arrange marshmallows, about 1cm apart, over the top in a single layer. Return to oven.
Cook for a further 25 to 30 minutes, or until marshmallows are lightly golden and outer edge of slice is firm to touch. Remove. Cool completely in pan.
Lift slice out of pan. Cut into squares.