Preheat your oven to 350°F and grease a 9x13 inch baking dish (or 8x8 inch for thicker brownies). While the oven heats, whisk together the gluten-free flour blend, cocoa powder, baking soda, and salt in a large mixing bowl. This ensures even distribution of the leavening agent and prevents cocoa lumps in your brownies.

While the oven preheats, finely shred your zucchini and squeeze it very dry using a clean kitchen towel or paper towels—this step is crucial to prevent watery brownies. In a separate bowl, whisk together the oil, granulated sugar, room temperature egg, 2 tsp vanilla extract, and espresso powder until well combined. The espresso powder deepens the chocolate flavor without adding coffee taste, and I find it's the secret weapon that makes these brownies taste more indulgent.

Pour the wet ingredient mixture from Step 2 into the dry ingredients from Step 1 and stir until just combined—don't overmix, as this can make brownies tough. Fold in the prepared zucchini and chocolate chips gently until evenly distributed throughout the batter. Spread the batter evenly into your prepared pan and bake for 25-30 minutes, until a toothpick inserted in the center comes out with just a few moist crumbs. Let cool while you prepare the frosting.

In a microwave-safe bowl, combine the chocolate chips, almond milk, melted and cooled butter, and 1.5 tsp vanilla extract. Microwave in 35-45 second intervals, stirring between each interval, until the chocolate is completely melted and smooth. Add the icing sugar and whisk vigorously until you achieve a silky, spreadable frosting—I like to whisk rather than stir because it incorporates air and creates a fluffier texture.

Spread or drizzle the chocolate frosting from Step 4 evenly over the cooled brownie base, working quickly before it sets. Allow the frosting to cool and set completely at room temperature or in the refrigerator for 15-20 minutes before cutting into squares. This ensures clean cuts and prevents the frosting from smudging.