1. To make the homemade chocolate protein bars, first line the bottom of an 8 inch square pan (or any similar sized pan) with parchment paper.
2. If nut butter is not already soft, gently warm it up (in the microwave or in a saucepan on the stove top) until easy to stir.
3. In a medium mixing bowl, stir the protein powder and salt. Then stir in the water, optional sweetener, and nut butter until well combined.
*The amount of sweetener will depend on your own personal tastes, and if you are using sweetened or unsweetened protein powder and nut butter.
4. Smooth dough into the lined pan. Use a spatula or your hands and a second sheet of parchment paper to press down firmly, spreading the dough out evenly into pan. (Alternatively, you can simply form the dough into bar shapes with your hands.)
5. If adding the chocolate topping, carefully melt chocolate chips in the microwave or a double boiler.
6. Pour melted chocolate sauce evenly over the pan of protein bars, smoothing it out with a spoon or spatula.
7. Either refrigerate or let sit on the counter until the chocolate sets. Slice into bars or squares and enjoy.
8. Cover leftovers and store at room temperature for three days. Or refrigerate for up to two weeks or freeze for up to three months.