Preheat the oven to 375 degrees F and line two baking sheets with parchment paper.
Whisk together all the dry ingredients, minus the sugar and chocolate chunks, in a medium mixing bowl and set aside.
In a small sauce pan, heat the butter over medium heat and cook until it begins to brown, about 5 minutes. Stir constantly so as not to burn it, you're just trying to brown it. Transfer to a large mixing bowl, add the coconut oil and let cool for 5 minutes. Add the sugar and beat with an electric mixer until incorporated. Add the tahini, vanilla and flax eggs and beat until combined.
Pour in the flour mixture and beat on low until just incorporated. The mixture will be that of a thick brownie batter, not as doughy as normal chocolate chip cookies. If the mixture seems dry, add some almond milk, 1 tablespoon at a time. Fold in the chocolate chunks and walnuts.
Scoop 1 heaping tablespoon of dough onto the cookie sheets, spacing the cookies about 1" apart. Press down with the back of a fork to flatten them slightly.
Bake in the center of the oven for 14 minutes, switching/rotating the sheets half way through.
Transfer to a wire rack, allow to cool for 5 minutes (if you can resist that long!), and enjoy!