Preheat your oven to 350°F (175°C). This ensures your brownies will bake evenly and achieve that perfect fudgy texture.
In a microwave-safe bowl, combine 4 ounces of dark chocolate and 2 tablespoons of coconut oil. Heat in the microwave in 20-second intervals, stirring in between, until melted and smooth. Remove from the microwave and let it cool slightly.
In a large mixing bowl, whisk together the nonfat vanilla Greek yogurt, coconut sugar, and eggs. Once well combined, add the melted chocolate mixture and stir until smooth.
In another bowl, mix together the cocoa powder, cornstarch, baking soda, and salt. This will ensure that all dry ingredients are evenly distributed.
Gradually add the dry ingredients to the wet mixture, folding gently until just combined. Be careful not to overmix, as this can lead to denser brownies.
Chop the remaining 1 ounce of dark chocolate into small chunks and fold them into your brownie batter. This will add delightful pockets of melty chocolate throughout.
Pour the batter into an 8x8 inch baking pan lined with parchment paper. Spread it evenly and smooth the top with a spatula. Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for at least 10 minutes before transferring them to a wire rack to cool completely. Once cooled, slice into squares and enjoy!
