Preheat oven to 350 degrees F. Line a 10x15 sheet pan with parchment paper, then spray the parchment and the sides of the pan with cooking spray.
In a large mixing bowl, stir together almond flour, cocoa powder, coconut sugar, baking soda, and sea salt.
In another bowl, whisk together eggs, butter, and vanilla extract.
Pour wet ingredients over dry ingredients and stir together until smooth.
Pour the batter into the prepared sheet pan, spreading the batter out evenly with a spatula. You want to get it as even as possible.
Bake for 12-13 minutes until just set.
Cool completely, then transfer the pan to the freeze for at least 2 hours. This will make the cookie layer much easier to handle while assembling.
Remove the cookie layer from the freezer and slice in half (cut the parchment paper on the bottom as well) so you have two same-sized rectangles. Place one rectangle in the freezer while you work.
Leave the other half of the cookie layer on the sheet pan and top with scoops of ice cream. Use a spatula to flatten out into an even layer. You may need to wait 10-15 minutes until the ice cream softens to do this.
Remove the other cookie layer from the freezer and place on top, pressing down gently. Freeze for at least 4 hours, preferably overnight.
Slice into 12 rectangles. Enjoy!