Make yout Flax Egg: Mix ground fllax seed and water in a small bowl. Set in the fridge for at least 5 minutes.

Melt your butter in the microwave or oven until it is just over half melted. If microwaving. use 30 second increments and check on it. Allow it to cool back to room temperature.

Add the white sugar, brown sugar, and vanilla extract. Cream with a hand mixer for about 1 minute, until a pale cream forms.

Add in your flax egg and mix on low for about 1 minute.

Add in your flour, baking soda, and salt. Beat on low for about 1 minute, until incorporated. Use a silicone spatula to scrape down the sides.

Lastly, fold in your chocolate chips and walnuts (if using). Cover bowl with plastic wrap and put in the fridge for at least 1 hour, up to 48 hours.

When ready to bake, preheat oven to 375 degrees. Line a baking sheet with parchment paper and roll about 2 tablespoons of dough into a ball. Place them a few inches apart since they will spread - you can use multiple baking sheets or bake in batches. Bake for 8 - 10 minutes, remove when the edges start to gain some color. The cookies will look a little puffy and not quite down, but TRUST ME. Let them cool for 2 - 5 minutes and they will finish caramelizing and solidifying outside the oven.