Preheat oven to 180°C. Place the 125g butter, flour and Chelsea Icing Sugar into a food processor and mix until the pastry forms a ball. Divide into 16 pieces and press the pastry into the bases and up the sides of non stick (or well greased) mini muffin tins. Refrigerate for at least 30 minutes. Divide the pecans between the chilled pastry cases, breaking the nuts as required. Mix melted butter, egg, Chelsea Soft Brown Sugar and vanilla until smooth and 'gluey' and spoon or pour carefully over the nuts. Do not overfill each pie. Bake at 180°C for 20 to 25 minutes. Lift pies from tin and cool on a wire rack.