In a bowl, combine your almond flour, coconut, walnuts and salt. Set aside.
In a double boiler (or a smaller pot that sits decently inside a large one partially filled with water) add your butter and turn the heat to medium.
Whisk as needed until the butter is almost melted, next add your cocoa powder and sweetener and whisk well until combined.
Then to add your egg, just whisk tiny bits of the hot cocoa/butter mixture into the egg ITSELF in a separate little bowl, whisking constantly and adding more every now and then until the egg is mixed with about 1/4 of the total mixture. Now you can add your egg mixture to the pot with the rest of the ingredients and whisk constantly until the mixture starts to become thick. (Doing this process just helps the egg from cooking and turning into scrambled eggs immediately when it hits the hot liquid).
Once the mixture has thickened, remove it from the heat and add it to your dry ingredients from earlier. Stir well until everything is combined. You may find using your hands here helps.
Press the chocolate dough into the bottom of an un-greased 11x7 inch pan (or 8x8inch pan). Try your best to make it as flat and even as possible. Set aside.