Prepare the flax egg by mixing together the flaxseed meal and water in a small bowl and setting it aside for 15 minutes to thicken.
Preheat to 350 degrees Fahrenheit. Line a large baking sheet with a silicone baking mat. You can also lightly grease the sheet with vegan butter or organic canola or avocado oil. Set aside.
In a large mixing bowl, add the vegan butter. Whip on high speed for about 30 seconds until smooth and airy. Add both sugars and mix again until fluffy, about 1 more minute. Add in the prepare flax egg and vanilla extract and mix again until well combined. Set aside.
In a medium mixing bowl, place the All Purpose flour, baking soda, cinnamon, walnuts and chocolate chips. Stir until well mixed.
Add the flour mixture to the butter and sugar mixture. With a large spoon, mix together until a smooth cookie dough is formed, scrapping the sides of the bowl as you go.
Scoop dough by the slightly heaping tablespoon. Place dough onto the baking sheet and continue until the sheet is full, leaving 1 inch between cookies.
Place the baking sheet into the oven and bake for 8 minutes. Check after 8 minutes, to see if cookies have flattened and spread. If not, gently flatten the tops of the cookies by tapping them a few times with a long spatula while in the oven. You can also remove them from the oven to flatten them if you don't have a long spatula. Return to oven after doing so.
After flattening, bake for an additional 5-7 minutes until golden brown.Cookies will still be soft when baked. Don't worry, they firm up as they cool.
Once baked, let cookies cool on the pan for at least 5 minutes. Transfer the cooled cookies to a baking rack with a spatula until fully set, about 15 minutes.