2⅔ cups granulated sugar
1⅓ cups whole milk
1⅓ cups unsalted butter, melted and slightly cooled
5 large eggs
¼ cup packed lemon zest (from 8 to 10 lemons)
1⅓ cups sour cream
5¼ cups plus 1 tablespoon all-purpose flour, divided
2½ teaspoons baking powder
1½ teaspoons kosher salt
3 cups fresh blueberries
Garnish: sparkling sugar
Preheat oven to 350°F. For metal loaf pans, spray 4 large or 8 small pans with baking spray with flour. For paper loaf pans, place pans on a large baking sheet
In a very large bowl, whisk together granulated sugar, milk, melted butter, eggs, and zest. Whisk in sour cream. In a large bowl, whisk together 5¼ cups flour, baking powder, and salt. Add flour mixture to sugar mixture, whisking just until dry ingredients are moistened.
In a medium bowl, toss together blueberries and remaining 1 tablespoon flour. Fold blueberries into batter. Divide batter among prepared pans. Sprinkle with sparkling sugar, if desired.
Bake until a wooden pick inserted in center comes out clean. For metal loaf pans: 50 minutes to 1 hour for large loaves, or 40 to 45 minutes for small loaves. For paper loaf pans: 45 to 50 minutes. Let cool completely in pans on wire racks.