Preheat oven to 350 degrees F. 

In the microwave, or on the stovetop, gently melt the butter and unsweetened chocolate until almost smooth. Remove from heat and continue to stir until all chocolate is melted. In seperate bowl, whisk sugars and eggs vigorously, until little bubbles come to top. 

Pour chocolate mixture into egg mixture, while whisking. Add cocoa powder and stir. Then add salt, baking soda, tapioca starch, and teff flour. Stir to combine and no streaks remain. Add vanilla extract, and stir. Then fold in chocolate chips and walnuts. 

Freeze batter for 13 minutes. Then remove and bake. 

Scoop heaping tablespoons of dough into rounds, and place on parchment lined cookie sheet. Bake for 11 minutes. Remove and let cool on pan for 2 minutes, then carefully transfer to a wire rack.