Line an 8x8- or 9x9-inch baking pan with parchment paper, leaving overhang on two sides like handles.

Place the peanut butter, honey, and coconut oil in a medium heatproof bowl. Set the bowl over a saucepan of water and bring the water to a simmer over medium to medium-high heat. (Do not let the water boil, and make sure the water does not touch the bottom of the mixing bowl.) Stir and heat until the mixture is smoothly combined. Remove the bowl from the saucepan and turn off the heat.

To the bowl with the peanut butter mixture, add the oats, protein powder, flaxseed, cinnamon, and salt. Stir to combine. The mixture will seem very dry at first but will come together as you stir. It won’t be sticky but should hold together when pressed (see recipe notes for more details). If the mixture is still fairly warm, pop the bowl into the refrigerator for a few minutes to let it cool, then stir in the chocolate chips. (Cooling the mixture will prevent the chocolate from melting. Don’t worry if they do melt a little—the bars will still be delicious!) Press evenly into the prepared pan and refrigerate for 1 hour or until firm.

Lift the bars from the pan using the parchment handles and transfer to a cutting board. Slice into bars of desired size and enjoy.