Preheat the oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper, leaving an overhang for easy removal.

Whisk together the cocoa powder, chocolate protein powder, baking powder, and sea salt in a medium bowl until evenly combined.

In a large mixing bowl, whisk the natural peanut butter, eggs, applesauce, vanilla extract, and coconut sugar until smooth and uniform.

Gently fold the dry ingredients into the wet mixture with a rubber spatula until just combined, taking care not to overmix.

Fold in the chocolate chips if using, distributing them evenly throughout the batter.

Pour the batter into the prepared pan and smooth the top with your spatula for an even layer.

Bake for 16 to 18 minutes, until a toothpick inserted into the center comes out with a few moist crumbs attached.

Allow the brownies to cool in the pan for at least 15 minutes, then lift out using the parchment overhang and cool completely on a wire rack.