First make the filling. This step can also be done the day before if you like. Toss your diced apples in the lemon juice to keep them from browning and add to a saucepan along with the 1/2 cup sugar, 1/4 tsp each cinnamon, ginger, nutmeg, cardamom, 1/2 tsp vanilla, 1 pinch salt, and 1 Tbsp cornstarch. Stir well to combine, then add the 1/4 cup apple cider, apple juice, or water. Bring up to a boil, stirring often to dissolve the sugar. Once at a boil lower the heat and simmer gently for about 5 minutes until the mixture is thickened and glossy. Transfer to a bowl to cool.
Preheat the oven to 350F
Now on to the crust. Pulse the 2 1/2 cups all purpose flour and 1 tsp salt a few times in a food processor to combine. Add the cold chunks of 1 cup unsalted butter to the bowl and pulse about 20 times until the mixture is grainy. (You can do this by hand if you prefer using a pastry cutter, forks, or your fingers.)
Add the 1/4 cup cold water, a little at a time, while continuing to pulse, until the dough just comes together when you pinch it between your fingers. Stop the machine to check it. NOTE: you may not need all of the water, but I always do.
Turn the dough out onto a floured surface and bring it together into a ball. If there is still any remaining dry flour make sure to knead that into the dough to get it all incorporated. If your dough is too sticky, add a touch more flour.
Cut the ball of dough in half, form two flat rectangles. Starting with one rectangle (cover the other with plastic) roll out to 8"x11", give or take. Transfer the dough to a sheet of parchment paper and place on a baking sheet. Spoon the cooled filling onto the dough, leaving about an inch of free space all around the edges.
Roll out the top crust to the same size, and carefully place over the filling, pressing down all around the edges to seal. Be sure to crimp or roll up the edges securely so the filling will not leak out during baking.
Bake for about 40 minutes until golden. Let cool before glazing.
To make the glaze whisk or stir the 1 cup (heaped) confectioner's sugar together with the water, a tablespoon at a time, until you get a glaze consistency. Spread it liberally over the top of the cooled pie. Let the glaze set up before slicing.
Store apple pie bars at room temperature for up to 3 days.