Preheat oven to 350 degrees. Generously spray a 10-inch angel food cake pan or bundt pan with cooking spray. In a large mixer bowl whisk together the egg white powder, sweetener and cream of tartar until there are no lumps
Attach the whisk attachment to a standing mixer, Turn mixer on to low and gradually add the water in. Allow the water to beat in after each addition. Once added gradually increase the speed to medium-high and allow to beat 15 to 20 minutes or until stiff peaks form
While the egg white mixture is beating in a large mixer bowl sift together the coconut flour and the salt until there are no lumps. Set aside until the egg white mixture is done mixing.
Once the egg mixture has come to stiff peaks gradually add the egg white mixture to the coconut flour mixture until fully combined and smooth. Fold in the vanilla extract until fully combined
Carefully spread mixture evenly throughout the prepared pan. Place the pan in the preheated oven. Bake at 350 degrees 40 to 45 minutes or until a tester comes out completely clean
Remove from the oven. Turn the pan upside down on a cooling rack and allow to cool at least 2 hours until cooled completely. Once cooled remove the cooling rack and place the pan upside down onto a serving platter
Carefully lift the cake pan and allow the cake to slide out of the pan and onto the platter. If desired top with the toppings of choice. Slice and serve immediately