Preheat your oven to 350F
In a mixing bowl, combine grated zucchini, eggs, granulated and brown sugar, and vanilla extract. Mix well till all the sugar is combined - it should be very liquidy. If it's not, let it sit for 3-4 minutes and let the zucchini work its magic. Then, add in the oil and yogurt. Mix well till incorporated.
In a separate bowl, combine the flour, baking powder, baking soda, salt, and cinnamon or pumpkin spice, then add that right in to the wet ingredients. Use a spatula to fold in the dry ingredients until just incorporated.
Grease a loaf pan with butter or avocado oil and pour the batter in the center.
Make the streusel by combining all ingredients in a plate or bowl. Use a fork to incorporate the butter into the flour and sugars. Once it looks like little pebbles, sprinkle it right on top of the batter in the loaf pan being sure to spread it across the entire surface. Place in the oven on the lower rack and let it back for 55-60 minutes or until a toothpick inserted in the center comes out clean.
Let cool for a couple minutes and enjoy with a cup of tea, some ice cream, berries or alone as a little snack!