Crushed cashews or other nuts, for topping (optional)
Prepare the Cashew Butter Cookies using the directions here. The recipe should make 24 cookies, though you might want to make them a little smaller since these sandwiches can be very rich! Cool the cookies on the baking sheet for 10 minutes, then move them to a cooling rack to cool completely. You can put the cookies on a plate in the freezer to help speed up the process!
Once the cookies are cool, prepare the banana ice cream. I've found that 2 large bananas create enough ice cream to fill about 6 cookie sandwiches, so use that as your guide when deciding how much ice cream to make. If you want to fill all of the cookies you'll probably need about 4 frozen bananas. I only wanted to fill half of of the cookies (so I could have leftover cookies to enjoy, too), so I used 2 frozen bananas, plus 1 tablespoon of organic peanut butter to make the ice cream extra-creamy. To prepare the ice cream, it helps if you cut the bananas into small pieces or coins so that they can break down quickly and evenly in a food processor. (I just used my hands to snap them into manageable chunks.) Place the bananas, and nut butter if using, into a small food processor or blender and add a couple tablespoons of water to help facilitate blending. Blend and scrape down the processor until the bananas have a smooth, ice-cream-like texture. (Add more water if you need to-- I ended up adding a 1/4 cup total.)
To make the ice cream sandwiches, arrange 6 to 12 of the cookies bottom-side-facing-up on a large plate or baking sheet. Add a generous scoop of banana ice cream to each one, then place another cookie on top of the ice cream to create a sandwich. Place the sheet of cookies in the freezer to firm up, at least 1 hour before serving.
For an extra decadent treat, I like to dip half of these cookies in melted dark chocolate and sprinkle them with crushed nuts. To melt the chocolate, simply use a double boiler (I use an oven-safe bowl over my 2-quart saucepan filled with 2 inches of water) and stir until melted. Use a spoon to pour the melted chocolate over the frozen cookies then quickly sprinkle them with crushed nuts before the chocolate hardens. Return each chocolate-coated cookie to a plate lined with parchment paper to prevent sticking. Serve frozen and enjoy!