Poppy seeds add a delicate crunch to this savory, cheesy zucchini loaf.
Preheat oven to 375 degrees. Brush a standard 9-by-5-inch loaf pan with butter and dust with flour, tapping out excess.
Place zucchini in the center of a clean kitchen towel or a few layers of cheesecloth. Gather into a tight bundle and squeeze out as much excess liquid as possible; set aside. In a large bowl, whisk together flour, sugar, salt, pepper, baking powder, baking soda, and poppy seeds, 30 seconds. Add 1 cup cheese; toss to evenly coat in flour mixture. In another bowl, whisk together butter, eggs, sour cream, and zucchini until smooth. Make a well in flour mixture and pour zucchini mixture into it. Stir together just until combined and no dryflour remains (do not overmix). Transfer to prepared pan. Top evenly with remaining 1/2 cup cheese.
Bake until a tester inserted into center comes out clean, 1 hour to 1 hour, 10 minutes. Let cool in pan 10 minutes, then transfer loaf to a wire rack and let cool completely. Bread can be stored at room temperature, wrapped in parchment-lined foil, up to 3 days.