01 - Preheat oven to 350°F. Line a baking sheet with parchment paper.
02 - In a small bowl, mix ground flaxseed with water. Let sit for 5 minutes until thickened.
03 - In a large bowl, whisk together the flour, cocoa powder, baking soda, and salt until well blended.
04 - In another bowl, whisk sugar, melted coconut oil, almond milk, vanilla, and the prepared flax egg until smooth and fully incorporated.
05 - Add the wet ingredients to the dry mixture. Mix until just combined, being careful not to overmix.
06 - Fold in chocolate chips and walnuts if using, distributing evenly throughout the dough.
07 - Scoop tablespoon-sized amounts of dough onto the prepared baking sheet, spacing about 2 inches apart to allow for spreading.
08 - Bake for 10-12 minutes, until cookies are set around the edges but still soft in the center.
09 - Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.