Preheat Oven to 350 degrees F.  Line a 9X13 pan with parchment paper.

In a mixing bowl, combine the all-purpose flour, powdered sugar, and salt to create a dough. Cut the cold butter into slices and add it to the flour.  Mix using an electric mixer until the mixture has coarse crumbs.

Press the crust mixture evenly in the prepared pan and bake for 15-18 minutes or until the crust is golden brown.

Make the pineapple mixture.  In a mixing bowl, whisk thawed pineapple juice concentrate, sugar, eggs, flour, cornstarch, salt, and vanilla.  Whisk until combined and smooth.

When the crust is done baking, carefully pour the pineapple mixture over the hot crust.  Pop back into the oven and bake for 35-28 minutes or until the mixture is set and does not jiggle when gently shaken.

Remove the Pineapple Bars from the oven.  Once cooled, cover and let them chill in the fridge for up to four hours.

Dust the cooled bars with powdered sugar and cut into squares.   You can serve them chilled or at room temperature.