Preheat oven to 350°F and spray a 9-inch tart pan with non-stick baking spray.
To make the crust, combine flour, powdered sugar, and salt in a bowl.
Add butter and stir until it is thoroughly combined and dough forms.
Press firmly into the bottom of the prepared 9” tart pan.
Bake for 10 minutes, or until the crust just begins to brown.
While the crust is baking make the filling. Whisk eggs, sugar, and salt together in a bowl.
Pour into a saucepan and heat over low-medium heat, whisking constantly. Slowly stir in the lemon juice.
Continue stirring until thickened; this should only take a few minutes.
Remove from heat and stir in the butter until it is incorporated.
Pour into the crust and bake for 10 more minutes. The center should still jiggle a little—that’s okay! It will set up as it cools.
Allow the tart to cool for about 30 minutes at room temperature. Then, refrigerate until ready to serve.
I served with whipped cream sprinkled with a bit of rosemary.