You can't use pure 100% cocoa chocolate like Barker's chocolate in this recipe. It's an unsweetened chocolate variety, and the cups will be very bitter and not sweet at all with this option. The best options are: - Sugar-free stevia-sweetened chocolate bars or chips - many brands provide tasty keto chocolate like Choc Zero. Don't buy maltitol sugar-free chocolate. It raises your blood sugar. It's not keto-friendly or gut-friendly either. - Dark chocolate with 85% cocoa. This is a higher carb option but a keto-friendly option if you can't find sugar-free stevia-sweetened chocolate where you live.