Healthy Zucchini Coffee Cake for 12

Instructions:

1. Preheat the oven to 350°F (175°C). Grease a 9-inch square baking pan or line it with parchment paper.
2. Grate the zucchini using the fine side of the grater. Pack it tightly into a measuring cup without squeezing out the juices.
3. In a large mixing bowl, whisk together the whole wheat pastry flour, all-purpose flour, sugar, baking soda, baking powder, salt, and ground cinnamon until no clumps remain.
4. Create a well in the center of the dry ingredients. Add the plain Greek yogurt, melted coconut oil (or butter), eggs, and vanilla extract. Stir with a spatula until just combined.
5. Gently fold in the grated zucchini until evenly distributed, being careful not to overmix.
6. In a small bowl, rub the cold cubed butter into the all-purpose flour, brown sugar, and cinnamon using your fingers or a pastry cutter until a crumbly streusel forms.
7. Spread the batter into the prepared pan and sprinkle the cinnamon streusel evenly over the top.
8. Bake for 45 minutes or until a toothpick inserted into the center comes out clean.