To make the cashew filling: Put the water, sugar and salt into a medium saucepan and stir it with your finger to combine. Use a wet hand to wipe down the sides of the pan. Heat the mixture over medium heat; when the sugar is dissolved and the liquid begins to boil, wash down the sides of the pan with a pastry brush dipped in cold water. Continue cooking until the sugar begins to caramelize; swirl the pan occasionally so the sugar cooks evenly. When the sugar is deep golden brown, add the cashews and cream slowly (mixture will bubble up). Cook the mixture at a boil to thicken the liquid for about 2 minutes. Remove from the heat, pour into a heatproof bowl, and let stand until cool.
To make the almond cream: Put the butter, sugar and salt into a food processor and pulse until evenly combined and no lumps of butter remain. Add the almond and all-purpose flour and pulse until just combined. Scrape down the bowl with a rubber spatula. Add the eggs, one at a time, pulsing between additions until combined. Add the vanilla and run the processor motor until combined and smooth. Transfer the cream to a bowl and refrigerate until ready to use.
To assemble the bars: Spray an 8-x-11-inch glass baking dish with cooking spray. On a lightly dusted work surface, roll the dough out into a 10-x-13-inch rectangle. Transfer the dough to the baking dish and press it evenly into the corners and up the sides of the dish; it should come about 1 inch up the sides. Refrigerate for about 20 minutes.
Remove the crust from the refrigerator. With a rubber spatula, stir and loosen the cashew filling until it is spreadable. Transfer to the dough-lined dish and gently spread it evenly over the crust, being careful not to tear the dough. Pour the chilled almond cream over the filling and spread it evenly. Refrigerate for 30 minutes.
Preheat the oven to 375°F.
Bake in the center of the oven, rotating the pan halfway through, until evenly golden brown on the top and bottom, about 40 minutes. Cool completely in the pan on a rack before cutting into 1-x-2-inch rectangles.