Preheat the oven to 350°F. Lightly grease an 8×8″ or 9×9″ baking dish and set aside.In a large measuring cup or small bowl, whisk together tahini (or preferred vegetable oil) with milk and vanilla extract until smooth. Add the coconut sugar and stir to combine.In a separate large bowl, add the spelt flour, cocoa powder, baking soda, and salt. Whisk to combine. To the bowl, add the shredded zucchini and pour the liquid ingredients over top. Stir until flour is evenly incorporated then fold in chocolate chips.Transfer the batter to the greased baking dish and spread to the sides using a spatula. Bake in the oven for about 30 minutes, or until cooked through. Allow to cool completely before frosting. Spread a layer of frosting on top and cut into 16 squares. Serve and enjoy!