Preheat the oven to 350 degrees F. Set out two 9X5 inch loaf pans. Spray the pans with nonstick baking spray. Then cut two parchment paper stripswide enough to line the bottoms and long edges of the pans. Press them into the pans. Set aside.
Set out an electric stand mixer. In the mixer bowl, combine 3 ¼ cups flour, sugar, baking powder, baking soda, salt, cinnamon, and nutmeg. Mix well.
Use a cheese grater to grate 2 cups of zucchini. Press the shredded zucchini with paper towels to remove most of the moisture. Then toss it with ¼ cup flour. (To help it mix evenly into the loaves and not sink to the bottom. This also helps the chocolate chips not all sink to the bottom. You can flour the chocolate chips too, but the flour doesn’t stick to them as well.)
Turn the mixer on low and mix in the eggs, oil, buttermilk, and vanilla extract. Scrape the bowl with a rubber spatula. Then mix in the grated zucchini and lemon zest. Toss the chocolate chips with 1 tablespoon flour then mix them into the batter by hand. (You can reserve a handful of chocolate chips, if you like, to sprinkle on top of the loaves, but it’s not necessary.)
Divide the batter evenly between the two loaf pans. Bake for 55-60 minutes, or until the tops are golden and a toothpick inserted deep into the center of the loaves comes out clean.
Remove from the oven and cool for 20 minutes in the pans. Then lift them bread out of the pans by the edges of the parchment paper, and place on a cooling rack or cutting board. Cut with a serrated knife and serve.
Wrapped in plastic wrap or stored in an airtight container, homemade zucchini bread will keep well for 5-6 days at room temperature.