Use a paddle attachment at medium speed in a stand mixer to cream the softened butter and icing sugar. Mix until smooth and creamy – generally this will take about 2 minutes.
Add egg and half of the flour. Use a slow machine speed to mix until the flour is incorporated.
Remove the bowl from the machine before adding the ground almonds and the remaining flour.
Bring the pastry together by hand but avoid overworking it.
Wrap your pastry with cling film / plastic wrap before refrigerating it for at least 30 minutes. You can leave it to chill for up to a couple of hours.
Grease a 25cm (10 inch) loose bottomed flan tin.
Roll out your pastry between two sheets of baking parchment to prevent it sticking to work surface and rolling pin.
Make sure the pastry circle is the right size for your flan tin. The circle needs to be slightly larger than the diameter of your flan tin plus twice the tin depth. The ideal pastry thickness should be that of a £1 coin (3 mm / ⅛ inch.)
Carefully line your flan tin with pastry, gently pressing the pastry to follow the tin’s shape. Try not to stretch the pastry, and patch any cracks that might appear.
Use a sharp knife to trim off excess pastry.
Prick the bottom of the pastry case with a fork and then refrigerate for at least 15 minutes.
Line your pastry case with baking parchment and fill with ceramic beans, rice or dried beans.