Whisk together the salt and flour in a medium sized bowl. Set aside.
In a large bowl, beat softened butter using electric mixer or stand mixer until pale and soft.
Add in sugar and continue to beat until fluffy consistency reached.
Slowly add in beaten egg and mix until incorporated.
Next, add the flour mixture in and beat until crumbly mixture achieved.
Work the dough with your hands, creating a ball. Flatten slightly into a disc shape.
Wrap in plastic wrap and place in freezer for about 10-15 minutes.
Preheat oven to 400F
Spray a tart or pie pan with non-stick cooking spray.
Remove dough from freezer. Over a lightly floured surface, roll out the dough until disc is flattened to about 1/8 inch.
Transfer dough into pie pan. If the dough tears, don't worry. Simply press the dough into the pie pan as evenly as possible.
Place pie pan in the freezer for another 10 minutes.
Prick holes in the tart dough with fork. Bake for 5 minutes at 400F. Then another 15 minutes at 350F.
Remove from heat. Immediately brush with beaten egg white to seal the crust. Let cool. Can be made ahead and refrigerated.