Heat your oven to 350°F and line an 8x8 inch baking pan (or 9x9 inch if you prefer thinner brownies) with parchment paper, allowing some overhang on the sides for easy removal later. This prep work takes just a minute but ensures your batter goes into a ready-to-use pan, which is crucial for even baking.
In a medium bowl, whisk together the flour, sifted cocoa powder, and salt. Sifting the cocoa is essential—it removes lumps and ensures even distribution of cocoa flavor throughout the brownies. I always give this mixture a good whisking even after sifting the cocoa to break up any remaining clumps and incorporate air, which helps the brownies rise slightly during baking.
In a large bowl, whisk together the melted and cooled butter, sugar, and vanilla extract until well combined. Make sure the butter has cooled to room temperature before mixing—warm butter can affect the texture of the final brownies. Whisking these ingredients together creates a foundation that will bind with the yogurt and help distribute moisture evenly throughout the batter.
Add the yogurt to the butter-sugar mixture and stir until completely combined and smooth. The yogurt replaces the eggs in this recipe and provides moisture and a slight tang that enhances the chocolate flavor. I prefer Fage 5% because its thicker consistency and higher fat content create a denser, more fudgy texture than thinner yogurts.
Pour the wet ingredient mixture from Step 4 into the bowl with the dry ingredients from Step 2. Stir until just combined—don't overmix, as this can develop gluten and make the brownies tough. Stop as soon as you no longer see streaks of dry flour; a slightly lumpy batter is actually what you want here.
Gently fold 3/4 cup chocolate chips into the batter using a spatula, then pour the batter into your prepared pan. Spread it evenly and smooth the top. Sprinkle the remaining 1/4 cup chocolate chips over the surface—these will partially melt into the batter during baking, creating pockets of rich chocolate throughout.
Bake for 20-24 minutes, until a toothpick inserted into the center comes out with just a few moist crumbs (not completely clean—this keeps them fudgy). Let the brownies cool completely in the pan before cutting, about 1-2 hours. This cooling time allows them to set properly and makes them easier to slice cleanly. Use the parchment overhang to lift the entire brownie block out of the pan for neat cutting.