With the dough blade in a food processor add the flour, powdered sugar and salt. Pulse a few times to combine.
Add the diced butter and mix just until the dough resembles a course meal.
Add in the egg and pulse until the dough just comes together, allow a little of the dry mix to remain, ensuring you don't over mix.
Place the dough onto a lightly floured surface and gently knead the dough until combined.
Roll the dough into a log, a couple inches high. Wrap in a piece of plastic wrap and place in the freezer for about 15 minutes.
Once the dough is slightly hardened slice into approx 1/4-1/2 in rounds.
Place on a lined baking sheet and bake for approx 12 minutes or until the bottoms and outermost edges are very lightly browned.
Make the glaze while the cookies cool slightly. In a small bowl mix together the powdered sugar, lemon juice and a bit of lemon zest. Spoon the glaze over top the cookies and finish with a dusting of powdered sugar.
*if you aren't going to serve right away, after glazing the cookies put them in the fridge for 10 mins to allow the glaze to set quicker. Once set they can be frozen in an airtight container. Dust with powdered sugar right before serving*