Preheat your oven to 350°F (175°C). Line an 8x8 inch square baking pan with parchment paper, allowing some overhang on the sides for easy removal later.
In a large mixing bowl, use a hand mixer or stand mixer to whisk the liquid egg whites until they form firm, stiff peaks. Add the lemon juice and continue whisking for just a few more seconds to help stabilize the mixture.
In a separate medium bowl, whisk together the cocoa powder, chocolate protein powder, monk fruit sweetener, baking powder, and the pinch of salt until all the dry ingredients are perfectly combined.
Carefully add about half of your dry mixture into the whipped egg whites. Using a spatula, gently fold it in until just combined. Then, add the remaining dry mixture and continue to fold very carefully until no dry spots remain, being sure not to deflate those airy egg whites.
Now, gently fold in the unsweetened almond milk and vanilla extract. Follow by folding in about half of your dark chocolate chips.
Pour the brownie batter evenly into your prepared baking pan. Sprinkle the remaining dark chocolate chips over the top for extra chocolatey goodness.
Place the pan in your preheated oven and bake for 21-26 minutes. The brownies are ready when they appear set, and a toothpick inserted into the center comes out mostly clean.
Remove the brownies from the oven and let them cool completely in the pan on a wire rack. This is crucial for them to firm up properly. If you wish, sprinkle with a dash of flaky sea salt before slicing into squares and savoring your delicious, healthy treat!