Crust: Combine flour, sugar, and salt in a food processor. Pulse a few times to mix. Add in butter and pulse a few times to break the butter down into pebble-size pieces. With the food processor running, drizzle in ice water. The dough should stick together when pressed between your fingers. (If dough doesn’t stick together, add more water 1 tablespoon at a time.)
Lay out a sheet of plastic wrap. Dump dough onto the plastic wrap and shape into a disc. Cover tightly with the plastic wrap and refrigerate until ready to use.
Preheat oven to 350ºF (175ºC).
Generously spray a 9 or 10 inch (23 or 25 cm) tart pan with nonstick spray. On a floured surface, roll out the pie crust into a circle that is 2–3 inches (5-7.5 cm) bigger than your tart. Lift crust into the tart pan and press against the sides of the pan. Trim the edges of the dough so that it is level with the top of the pan.
Filling: Whisk eggs, sugar, McCormick Vanilla Extract, and salt in a medium bowl, then set aside.
Place butter in a saucepan over medium heat. Let butter completely melt and foam, stirring occasionally. Keep stirring as the foaming subsides and the butter begins to brown. Once butter browns, quickly transfer to a bowl and let cool for 10 minutes. Whisk browned butter into the egg mixture. Whisk in flour and lemon zest.
Arrange sliced apples in a spiral pattern on the pie crust. Pour custard over apples, until custard reaches ½ inch (1 ¼ cm) below the top of crust (if using a 9-inch (23 cm) pan, you will have a little custard left over).
Place in oven and bake for 50 minutes (cover with foil if the top starts browning too much, or until custard is set).