Preheat your oven to 425°F.
In a large mixing bowl, whisk the eggs, oil, brown sugar, yogurt, milk and vanilla extract together until well combined.
Place the finely grated zucchini on a clean tea towel or a triple layer of paper towels. Then squeeze all of the extra moisture out over the sink.
Stir the zucchini into the wet ingredients.
In a separate small mixing bowl, combine the flour, cocoa powder, baking powder, baking soda, coffee, if using, and salt.
Pour the dry ingredients into the wet and gently fold until almost combined.
Add in the white chocolate chips and fold until combined. Be sure not to overmix or your muffins will turn out very tough.
Grease or line 12 cupcake tins and then divide the batter between them. The tins should be full.
Bake for 7 minutes at 425℉, then drop the temperature to 350℉ and bake for an additional 12-14 minutes or until centre is set and a toothpick comes out clean.
Allow the muffins to cool for 5 minutes in the pan, then remove to a wire rack to fully cool. Store in an airtight container for up to 2 days or in the freezer for up to 3 months.