Make the chia egg by mixing the water and chia seeds together in a small bowl. Set this aside for 15 minutes
Now brown the softened butter. To do this, cut the butter into small pieces and add it to a stovetop pan over medium heat. Keep stirring it around constantly and let it bubble and turn a golden brown color. When it has changed color (you can also smell it at this point - it should only take about 4 minutes of stirring), remove it from the heat and let it cool for 5 minutes before using. Butter does burn easily though, so if you can smell it browning, see it bubbling and see the color change, then it's time to turn off the heat.
After waiting 5 minutes for the butter to cool, beat the brown sugar and browned butter in a bowl with an electric mixer for 2 minutes.
Add in the chia egg and vanilla, and beat it again for a minute.
Mix the dry ingredients in a separate large mixing bowl, except the chocolate chips.
Once the dry ingredients are mixed together, slowly mix them into the wet ingredients using an electric mixer or a whisk. Add in the chocolate chips last, then stir to combine.
Once a dough is formed, let the dough sit in the fridge for 30 minutes.
In the meantime, preheat the oven to 350 degrees. Grease a cookie / baking sheet or line a baking tray with wax paper / parchment paper.
Once the cookies have chilled, shape 12 balls using your hands or a cookie scoop. Evenly separate them on the cookie sheet and bake cookies for 9-10 minutes.
If you like a more crispy cookies, leave it in there for an extra minute (10 minutes). Otherwise, take it out at 9 minutes. Let the baked cookies cool for 20 minutes on a wire rack or on the baking tray once they are out of the oven.
Enjoy! See storage notes below.