Preheat oven to 350ºF. Line an 8×8 baking pan with parchment paper and set aside.
In a small saucepan, add 2/3 cup of chocolate chips and melted butter. Bring the saucepan to a low-heat and stir gently the chocolate chips until it’s totally melted and smooth. Then, remove from heat, let it cool down and set aside.
In a medium bowl, add sugar, eggs and vanilla and whisk together until smooth.
In the same bowl, add all the dry ingredients (almond flour, cocoa, baking soda, and salt) and mix well to combine.
Now, pour the melted chocolate into the same bowl and stir to combine.
Fold in 1/3 cup chocolate chips and walnut.
Pour batter into your prepared pan and smooth the surface.
Bake for about 20-25 minutes, or until edges are set and the center is just a little underdone. When you remove from the oven, the remaining heat should set the center. Don’t over bake it because it may be dry and crumbly.
Place the baking pan on a wire rack and let it cools down for 10 minutes. Then, cut into squares. Enjoy!