1. In a bowl, add butter (softened), fine salt and sugar. Mix until well combined.
2. Add egg and mix well until smooth.
3. Add flour and almond flour. Using a rubber spatula, knead lightly until the dough just comes together. Divide it into 2 portions and shape each of them into a disk. Wrap loosely in plastic wrap and chill at least 1 hour before using.
If you don't use it for a few days, then place into a ziplock bag and freeze.