Preheat your oven to 350°F (175°C) and line an 8x8-inch baking pan with parchment paper.
In a mixing bowl, combine the whey protein powder, unsweetened cocoa powder, almond flour, baking soda, and a pinch of salt.
In another bowl, whisk together the Greek yogurt, honey (or maple syrup), almond milk, eggs, and vanilla extract until well combined.
Pour the wet ingredients into the dry ingredients and stir until you have a smooth batter.
Pour the batter into the prepared baking pan and spread it evenly.
Bake in the preheated oven for about 20 minutes or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs.
Allow the brownies to cool in the pan for a few minutes before transferring them to a wire rack to cool completely.