In a large bowl mix butter with powdered sugar until light and fluffy. Add egg and continue mixing until well combined and creamy.
In a medium bowl whisk flour with ground almonds and salt and add to butter mixture.
Use a wooden spoon to incorporate the flour mixture into the butter until combined. Add milk if necessary. Make sure you don’t overwork the dough.
Wrap the dough with plastic wrap, form into a disc and refrigerate for at least 30 minutes.
Preheat oven to 350F (180C).
Roll the dough between two pieces of parchment paper or plastic wrap until it's about 12in (30cm) in diameter.
Press the dough onto the bottom and edges of a 8- 9 inch (20-23cm) tart pan. Cut the excess dough.
Refrigerate for about 30 minutes before baking.
Prick the dough with a fork, line a parchment paper over the dough. Fill with dry beans, rice or pie weights.
Bake for 15 minutes. Remove the weights and the parchment paper. Return to oven for another 10 to 15 minutes. Allow to cool before filling.
Reduce oven temperature to 320F (160C).