Line a rimmed baking sheet with parchment paper (I use a 13”x18” “half sheet”-sized jelly roll pan but a small difference in size won’t make a big difference in your crackers). Make sure your parchment goes right up to each edge of the pan. Preheat oven to 300F.
Place all ingredients in a blender or food processor and blend until a completely smooth puree is formed, about 2-4 minutes (it doesn’t matter if you don’t have exactly 2 cups of plantain puree as long as you are fairly close, say within ¼ cup). This blends easier if your plantains are at room temperature and your coconut oil is melted.
Pour batter (it should look very much like hummus) onto the prepared baking sheet. Use a rubber spatula to smooth it out and cover the entire sheet uniformly (this might take a couple of minutes, but it doesn’t need to be perfect). The batter should be about 1/8” thick.
Bake for 10 minutes. Remove from the oven and score the cracker batter with a pastry wheel, pizza cutter, or pastry scraper (which is what I used). You can make whatever size cracker you like. The crackers will pull away from each other slightly while cooking and shrink up a bit, but not much. I like fairly small crackers, about 1½” squares, but these will work even for quite big crackers.
Place back in the oven and bake for 50-55 minutes, until golden brown (if you have slightly thicker crackers, this may take longer… I’ve occasionally had batches that took 70 minutes before being done). Remove from oven and let cool slightly on the pan. Move to a cooling rack (you will probably be moving fairly big pieces of several crackers stuck together). Once completely cool, you can break apart any crackers that are stuck together.
Store in an airtight container at room temperature. Enjoy!