Preheat the oven to 350°F (175°C) and coat an 8x8 inch baking pan with non-stick spray or parchment paper.

In a large mixing bowl, whisk the egg, applesauce, maple syrup, and vanilla extract until the mixture is homogenous.

Sift the chocolate whey protein powder, cocoa powder, baking soda, and salt into the wet ingredients to prevent clumping.

Using a silicone spatula, fold the dry ingredients into the wet until a thick batter forms, taking care not to overmix.

Fold in the mini dark chocolate chips evenly throughout the batter.

Transfer the batter to the prepared pan and spread into an even layer using the spatula.

Bake for 18 to 22 minutes; the brownies are done when the edges are firm but the center remains slightly soft.

Remove from the oven and allow to cool completely in the pan to ensure the structure sets before slicing into 12 equal squares.