In a mixing bowl, combine the flour, powdered sugar, salt and give it a quick mix.
Next, add the cold butter. You can cut it into small pieces, or you can use a grater and grate it like I do. Rub the butter into the dry ingredients until you get a crumbly mixture.
Next, add the egg yolk and one tablespoon of cold water. Using a spoon, start mixing the dough. Then transfer the dough onto a work surface and knead the dough by hand until it comes together. The dough should turn out soft and not stick to your hands. Cover the dough with plastic wrap and refrigerate for 30 minutes.
When the dough has chilled, dust the work surface with flour, place the chilled dough and roll it out thin, about 1/8 of an inch. Lay the dough in a 9-inch tart pan and push it into the bottom and the sides of the pan. Roll the rolling pin across the top to cut off the excess pastry. Poke the bottom of the pan with a fork and freeze the dough for 30 minutes.
For the filling, in a large mixing bowl combine the condensed milk, lemon juice, lemon zest and eggs. Whisk all together until you get a smooth consistency.
After 30 minutes in the freezer, place the tart pan onto a baking sheet and bake at 350 degrees Fahrenheit for 20 minutes or until slightly golden. Fill the tart crust with the filling, smooth with a spatula and bake for another 20-25 minutes. The surface of the tart should be firm. Let the lemon tart cool down to room temperature, then refrigerate for at least an hour.
