Make the double pie crust with a food processor: Place cold butter, flour, salt, and sugar in a food processor and pulse 4-5 times. Pea-sized butter flakes should still be visible. Add one tablespoon water after another and pulse 1-2 times after every tablespoon. Stop adding water when the dough starts to clump and holds together when you press the crumbs together in your hand.
If you don't have a food processor, then make the double pie crust with a pastry cutter or two forks instead: In this case mix together flour, salt, and sugar in a large mixing bowl. Then add butter and cut it into the mixture until it resembles coarse meal with pea-sized butter flakes. Then add water little by little until the texture starts to clump.
Divide pie crust into two halves and form 1 - 1.5 inch thick discs without kneading. Cover tightly with plastic wrap and refrigerate at least 2 hours or up to 2 days.
Preheat oven to 375°F (190°C).
On a lightly floured surface roll out the first dough disc into a 12-inch circle. Transfer to a 9-inch pie dish. The edges of the pie crust should hang out of the baking form. Set aside
In a large bowl stir together pineapple, sugar, salt, lemon juice and stir to combine. Add cornstarch and stir until combined. Fill into the pie crust. Then cut butter into small pieces and put on top of the filling.
Roll out second dough disc and cut into 1-2 inch strips. Arrange strips in a grid on top of your filling and lay over and under one another carefully. Seal and flute the edges. Brush with egg. Bake for 45-50 minutes. Cover the first 20 minutes with parchment paper to prevent it from browning too much. Let cool to room temperature and chill for 4 hours in the fridge. Store leftovers in an airtight container in the refrigerator up to 3 days.