Instructions:

• Melt a stick of butter and pour it into a large mixing bowl.
• Add the sugar, sourdough starter, and vanilla. and whisk it together.
• In a separate bowl, mix the baking soda, cocoa powder, flour and salt together thoroughly.
• Combine flour mixture with wet ingredients in the large bowl. The dry ingredients don't mix in well at all, but the zucchini will fix that. Let it rest while you shred the zucchini.
• Shred a small or medium zucchini with a box grater.
• Measure 4 cups of the grated zucchini into the dry brownie batter.
• Mix as good as you can, then let it rest for 15 minutes, then try again. At this point the zucchini should have released moisture and it should be mix together well. If not, it will release extra moisture as it sits.
• Let it sit at room temperature to ferment for 4-6 hours, or overnight in the fridge.
• Preheat oven to 350 degrees F.
• Line a 9x13 baking dish with parchment paper, or just spray the pan well.
• Mix 1.5 cups chocolate chips into the batter.
• Spread brownie mixture into the baking pan and bake in preheated oven for 30-35 minutes. Test brownies with a toothpick, if you can poke it into the center and it comes out with crumbs, it's ready.
• Let cool slightly on cooling rack before cutting.