This recipe makes 20 pieces at 2.5 net carbs each.
1/2 cup unsalted butter (see my comments above)
1/2 cup natural peanut butter
2 ounces regular full fat cream cheese, softened
1 cup granular Splenda
2/3 cup whey protein powder, vanilla flavor, which is 2 scoops
Melt the butter and peanut butter together in the microwave on HIGH for 1-2 minutes; whisk well. Whisk in the cream cheese until well blended and smooth. Whisk in the Splenda then the whey protein powder and blend well. Line a 7 x 5" baking dish with wax paper or nonstick foil. Spread the fudge mixture in the pan and chill or freeze until set. Cut into 20 squares. Store in the refrigerator or freeze.