To make the crust, combine all the crust ingredients in a food processor and blend until almost totally mixed. It should be slightly crumbly when poured out, but should be sticky enough to hold together when pressed into the bottom of the pan. If it's too dry, add another date, if it's too wet and sticky, add a few more almonds.
Spread the crust mixture evenly across the bottom of a parchment-lined or nonstick square pan, and freeze while you make the crumb topping.
To make the crumb topping, add all the ingredients to the food processor.
Do NOT blend, instead press pulse 10-20 times. We want this mixture to be roughly chopped, and to still have large pieces of nuts and apple for texture. Once you've pulsed enough so that the dates are broken up into small pieces, spread this mixture over the crust and freeze for 2 hours.
Cut the bars carefully to serve - they're delicate, so be careful when cutting. These are best enjoyed with a fork rather than picking up with your hands, so you don't lose all the crumbs.
