To make centers, melt 2 ounces of chocolate and macadamia nut milk in double boiler. Whisk gently to blend. Refrigerate about 2 hours or until firm. Form into 6 balls; refrigerate until needed.
To make cake, heat oven to 400°F. Spray six 4-ounce ramekins or custard cups with cooking spray. Melt 4 ounces of chocolate and butter in double boiler; whisk gently to blend. With an electric mixer, whisk eggs, yolks, sweetener, and vanilla on high speed about 5 minutes or until thick and light. Fold melted chocolate mixture and peanut butter protein powder into egg mixture just until combined. Spoon cake batter into ramekins. Place a chocolate ball in the middle of each ramekin.
Bake about 15 minutes or until cake is firm to the touch. Let it sit out of the oven for about 5 minutes. Run a small, sharp knife around inside of each ramekin, place a plate on top, invert and remove ramekin. Garnish with a dollop of whipped cream. Serves 6.