1cup(170g)chopped semisweet chocolate or good-quality chocolate chips that melt well (see note)
¼cup(21g)natural unsweetened cocoa powder
½cup(106g)packed light brown sugar
1large egg yolk
2cups(about 283g)finely shredded zucchini that has been wrung dry (see note)
1 ¼cups(178g)all-purpose flour
2cups(340g)chocolate chips or chunks
Preheat the oven to 350 degrees F. Lightly coat a 9x13-inch aluminum pan (see note) with nonstick cooking spray or line with foil and coat with cooking spray (for easier cleanup and to lift out the brownies in one slab after baking, if desired).
In a microwave-safe bowl (you can also do this in a pan on the stovetop), add the butter, chocolate chips, and cocoa. Cook for one minute increments, stirring in between, until the mixture is melted and smooth (don't overheat).
Add the brown sugar and white sugar; mix well. Add the vanilla and egg yolk and mix again until well-combined.
Stir in the baking soda and salt until well-combined.
Add the zucchini and stir until evenly mixed.
Add the flour and ONE CUP of the chocolate chips (or chunks) and stir until just combined (don't overmix).
Spread the batter evenly in the prepared pan. Sprinkle the remaining cup of chocolate chips over the top.
Bake for 25-30 minutes until the edges are set and the middle is soft (a toothpick inserted in the center will come out clean or with a few moist crumbs - but if there is wet batter on the toothpick, bake for a few more minutes). Don't overbake or the brownies can be dry. Let the brownies cool in the pan before cutting. These taste amazing chilled.
Chocolate Chips: my favorite chocolate chips for melting are the Ghirardelli or Guittard brand. I haven't had the best luck with other brands (Nestle/Hershey's), but use the chocolate chips you prefer (taste-wise) and you should be ok. Zucchini: I don't mess with any towels or contraptions for this recipe. I grate it using the fine holes of the shredding disk on my food processor and then just grab handfuls and squeeze over the sink before adding to the measuring cup/scale. You do want it as dry as possible (a key to not ending up with zucchini CAKE instead of zucchini BROWNIES), though, so if you want tips on how to wring it completely dry, here's a quick 2-minute video. For this recipe to get the 2 cups of DRY zucchini, I use about 2 small-medium size zucchini. Baking Pans: I always use metal baking pans for brownies - glass or ceramic pans don't bake as evenly in my experience. If you are using a glass pan, try decreasing the oven temperature to 325 degrees F so the edges don't overbake while the middle is still underdone. Also, brownies baked in a light colored metal baking pans may need more time (my metal baking pan has a darker coating).