Preheat your oven to 350°F and prepare a 9x13 inch baking dish by greasing it or lining it with parchment paper. Bring your eggs to room temperature if they aren't already—this helps them incorporate smoothly into the batter. Measure out all your ingredients and have them ready before you begin mixing, which helps you move efficiently through the next steps.

In a large bowl, whisk together the gluten-free flour blend, cocoa powder, espresso powder, brown sugar, granulated sugar, baking powder, salt, and cinnamon. Whisking thoroughly ensures the leavening agents and espresso powder are evenly distributed throughout, which prevents pockets of bitter espresso flavor and gives you consistent texture in every bite. I like to sift the cocoa powder into the mixture rather than just whisking it—cocoa can clump easily and sifting ensures it's fully incorporated.

While working on the dry ingredients, melt the chocolate chips in the microwave in 20-second intervals, stirring between each interval until fully melted and smooth—this prevents scorching. In a separate bowl, whisk together the room temperature eggs, light oil, non-dairy milk, and vanilla extract until well combined. Add the melted chocolate to the wet mixture and stir until fully incorporated and uniform in color.

Pour the wet ingredient mixture from Step 3 into the bowl of dry ingredients from Step 2 and fold together gently using a spatula or wooden spoon until just combined—don't overmix, as this can lead to dense brownies. Let the batter sit at room temperature for 15 minutes. This rest period allows the gluten-free flour blend to fully hydrate and helps the batter set slightly, which results in a more fudgy texture and better structure.

Pour the rested batter into your prepared baking dish from Step 1, spreading it evenly into the corners. Bake at 350°F for 30-35 minutes—the brownies are done when a toothpick inserted in the center comes out with just a few moist crumbs still clinging to it, not completely clean. I prefer my brownies slightly underbaked because gluten-free batters continue to set as they cool, and this keeps them fudgy rather than cake-like.

Allow the brownies to cool completely in the baking dish on a wire rack or cool surface—this typically takes at least 1-2 hours. Once cooled, slice into squares and serve. The cooling time is essential because the brownies continue to firm up slightly, making them easier to cut cleanly.