Preheat oven to 350 degrees F. Grease a non-stick 8x8 baking pan with cooking spray and line it with a parchment paper sling. Set aside.
Place almond flour, pecans, coconut sugar, salt, coconut oil, and vanilla into a food processor.
Process until the pecans have broken up to resemble a crumb and the ingredients have been fully incorporated.
Pour the mixture into the prepared pan, then gently, but firmly press into an even layer.
Bake in preheated oven for 10 minutes.
Allow to cool for 10 minutes while you make the filling.
Filling
Place cashews, coconut cream, lemon zest, lemon juice, maple syrup, vanilla, cornstarch, cream of tartar, and salt into a high powered blender (like a Vitamix) and blend until very smooth and creamy — there should be no lumps.
Pour into the slightly cooled crust then bake in the preheated oven for 25 minutes — it will still be quite jiggly in the center.
Cool at room temperature for 30 minutes.
Place in the fridge to set, at least 2 1/2 hours, but preferably overnight.
Right before serving, dust with powdered sugar, slice into squares, and enjoy!