Updated recipe:

Where it says:

Put these in food processer and “sift” together:
1 cup xylitol, powdered (Do not substitute. Xylitol holds water and makes a moister cake. Powder it in your food processor before adding other ingredients).
1 cup Now (brand) whey protein isolate, natural unflavored
1-1/2 teaspoons xanthan gum CHANGE THIS TO 1 TABLESPOON