Crush the biscuits into fine crumbs and mix together with the melted butter.

Press the crumb mixture onto the base and halfway up the sides of a well-greased 18 cm (7 inch) spring-form cake tin. Chill the biscuit crumb base for at least 1 hour.

Reserve 8 pecan nut halves for decoration, and chop the remainder finely

In a large saucepan, dissolve the marshmallows in the coffee, by heating gently and stirring frequently

Sprinkle the gelatine onto the hot water and stir, until it is clear and has dissolved completely

Carefully pour the gelatine into the marshmallow mixture, and stir well, to ensure that it is evenly mixed in. Leave the coffee and marshmallow mixture to cool, until it is almost set.

Whisk the egg white until it forms soft peaks, and fold this carefully into the fromage frais.

Fold the fromage frais into the coffee and marshmallow mixture with a metal spoon, incorporating as much air as possible, and making sure that the fromage frais is evenly blended.

Stir in the chopped nuts and pour the mixture onto the chilled biscuit base.

Chill the pie in the refrigerator for at least 3 hours, until completely set.

Remove the sides of the tin, and slide the pie carefully onto a serving dish. Decorate with the reserved nut halves.