Line an 8x8 inch baking pan with parchment paper, leaving some overhang on the sides.

In a mixing bowl, combine the rolled oats and protein powder.

In another bowl, mix the peanut butter and honey until smooth.

Pour the wet mixture into the dry mixture, and stir until well combined.

Fold in chocolate chips and nuts if desired.

Transfer the mixture to the prepared baking pan, pressing down firmly.

Refrigerate the pan for at least 1 hour to let the bars firm up.

Once chilled, lift the mixture out using the parchment overhang and cut into bars.