Put the butter and flour into a large mixing bowl. With your hands rub the butter into the flour until it resembles breadcrumbs. Next add the ground almonds and icing sugar and continue to rub the mix together.
Add the water and egg, then quickly mix it all together with your hands. Once combined you should be able to shape the dough into a ball. Wrap this ball of dough in cling film and leave in the fridge overnight.
Take your dough from the fridge and roll out. This gluten free dough will be a little 'wetter' and 'sticker' than regular dough so you need to try and roll it out quickly. Line your pie tin with the dough then set it aside.
Preheat your oven to 200c (400f). In an electric mixer, mix together the pumpkin, milk, syrup, cinnamon, salt and eggs until well mixed. Pour the filling into your unbaked pie shell then place in the oven. Bake for 10 minutes then reduce the oven temperature to 175c (350f) and bake for a further 40 or 50 minutes, The pie is completely cooked when a skewer inserted into the middle comes out clean.
Allow the pie to cool completely before decorating with pecans.