Combine the almonds, cocoa powder and salt in the food processor (I used this mini food chopper) and process until a fine powder is created. Add in the dates and vanilla extract, and process again until a uniform, sticky dough is formed. You may need to stop and scrape down the sides to help with even processing.
Transfer the cookie dough to a pan lined with parchment paper, and use your hands (wet hands can help prevent sticking) to shape the dough into a rectangle shape, about 1/4-inch thick. Place the dough in the freezer to set for 20 minutes, then use a large knife to cut the dough into 8 rectangular cookies. Return to the freezer while you prepare the ice cream.
To make the ice cream, you'll need to use the same food processor again. For easiest processing, cut the frozen bananas into chunks before blending, then combine them with the vanilla extract and 1-2 tablespoons of water in the food processor. Blend until completely smooth and creamy, like ice cream! (Add more water, if needed, to achieve this texture.)
Remove the chocolate cookies from the freezer, and place a large spoonful of ice cream on to four of the sandwich sides. Use the other four cookies to create sandwiches, and press the cookies together to even-out the ice cream middles. Place in the freezer to allow the ice cream to solidify, about 20-30 minutes, then serve! Store the sandwiches in a sealed container in the freezer.