Preheat oven to 350°F (175°C) and grease a small baking dish or line with parchment paper.
In a large mixing bowl, whisk together the Greek yogurt, maple syrup, egg, and vanilla extract until smooth.
Sift the cocoa powder into the wet mixture, then add the baking soda and salt.
Fold the ingredients together with a spatula until just combined, ensuring no dry clumps remain.
Stir in 1/4 cup of the chocolate chips.
Pour the batter into the prepared baking dish and smooth the top.
Sprinkle the remaining chocolate chips evenly over the surface.
Bake for 22-25 minutes or until a toothpick inserted into the center comes out with only a few moist crumbs.
Allow the brownies to cool completely in the pan for at least 30 minutes to set before slicing into 7 portions.