In medium bowl, mix the butter, collagen peptides, powdered sweetener, and peanut butter together. Spread mixture in the bottom of prepared pan.
In Pyrex or metal bowl over pot of simmering water, melt chocolate chips with the peanut butter, stirring until smooth. Pour melted chocolate over peanut butter mixture and spread evenly to cover top.
Refrigerate for at least an hour before cutting into squares. Keep in the refrigerator for snacking.
Video
Notes
It's best to use an electric mixer to ensure the peanut butter mix is well blended before spreading into the pan. Otherwise, you can get chunks of collagen or sweetener in the bars.Be sure to use a peanut butter with no added sugar. It should just be peanuts or peanuts and salt.I prefer using collagen peptide instead of whey powder as it's dairy-free. However, if you do use whey, look for an unflavored one with the least amount of carbs. If you can't find the powdered sweetener listed, a blend of ½ cup powdered erythritol with about ¼ teaspoon stevia extract powder can be used instead..