Make a lemon basil sugar by combining your granulated sugar with zest of one lemon, basil leaves in a high-speed blender, food processor, or mortar and pestle.
Preheat the oven to 350°F (176°C)
Prepare a 9x5 loaf pan with parchment paper, leaving some showing on the sides for easy removal. I also lightly grease with butter or cooking spray.
Add your butter to a small saucepan or to a microwave-safe bowl and melt on low until completely melted. Set aside to let cool.
Grate zucchini and set aside.
Whisk the flour, baking powder, baking soda, and salt together in a large bowl until combined. Set aside.
In a medium bowl, whisk the cooled butter, brown sugar, lemon basil sugar, eggs, room-temperature cream cheese, zest of one lemon, lemon juice from both lemons, and vanilla together until combined.
Pour the wet ingredients into the dry ingredients. Gently stir or whisk until combined. Gently fold in zucchini.
Spread the thick batter evenly into your prepared loaf pan. Bake for 55-60 minutes. Baking times vary, so keep an eye on yours, checking for doneness every 5 minutes at the 55-minute mark. The bread is done when a toothpick inserted in the center comes out clean.
Remove the bread from the oven and allow it to cool before removing from the pan.