Preheat oven to 350 degrees F (176 C) and lightly coat a baking sheet with non-stick spray.
Prepare flax egg by mixing flax and water in a large bowl. Set aside.
Measure out almond milk in a liquid measuring cup and add vinegar. Let set for a few minutes.
Add the sugar, melted coconut oil and vanilla to the flax egg and beat.
Add almond milk and beat again.
Add remaining dry ingredients to a sifter and sift over wet ingredients. Beat until well combined.
Add chocolate chips and fold in until just combined.
Spoon 1 Tbsp measurements of batter onto the greased baking sheet (leaving a small space in between cakies) and spread around and flatten a bit - you don't want mounds, but rather discs.
Bake for 10 minutes. Remove from oven, let set on tray for 5 minutes, then carefully transfer to a cooling rack to cool. Once cooled, pop cakies in the freezer to harden so they're easier to work with.
In the meantime, set your ice cream out so it begins to soften - about 15 minutes.
Once soft, use an ice cream scoop to scoop out 8 large balls of ice cream onto squares of plastic wrap (amount as original recipe is written // adjust if altering batch size). Fold the plastic wrap around the balls and squash them into thick discs. Twist off tops to cover and place back in the freezer to harden - about 30 minutes.
Once frozen, remove chocolate cakies and the ice cream discs from the freezer and carefully plop the ice cream on the top of one cakey (face down) and then top it with another cakey (face up). (SAVE the plastic wrap).
Use both hands to carefully press the cakies together around the ice cream, then place in a baking dish, re-wrap with squares of plastic wrap, cover with a lid and pop back in freezer.
Will stay fresh for up to a week.
*IMPORTANT: Before eating, either let your sandwich set out for about 15 minutes OR unwrap it and microwave on a plate for 20 seconds. The more frozen it is, the less you can taste its flavors. *These would be excellent dipped in dark chocolate and/or rolled in nuts before serving. *Nutrition information is a rough estimate.