METHOD

Place the 125g butter, flour and icing sugar in a food processor and run the machine until the pastry clumps together in a ball around the blade.
Divide into 16 balls and with floured hands press the pastry into the bases and up the sides of a non-stick mini-muffin tin. Refrigerate for at least 30 minutes; the pastry will set quite firm, and bake it cold like this.
Divide the nuts between the chilled pastry cases.
Mix the melted butter, egg, brown sugar and vanilla together until smooth and 'gluey', and spoon or pour carefully over the nuts. Do not overfill each little pie.
Bake in a preheated oven at 180c for 20-25 minutes, until the pastry is golden brown and the filling puffed and crisp.
Take out of the oven and leave in the mini-muffin tins for a few minutes until they are cool enough to handle.
Give each pie a little twist around to loosen the bottom, then carefully lift them out to cool completely on a wire rack.
They are delicious served warm and can be reheated easily and served with whipped cream or ice cream.