01 - In a large mixing bowl, combine flour, sugar, yeast, and salt. Whisk to distribute evenly.
02 - Add warm milk, melted butter, and egg to the dry ingredients. Mix until a sticky dough forms and all flour is incorporated.
03 - Knead the dough on a lightly floured surface for 8-10 minutes until smooth and elastic. Alternatively, use a stand mixer with dough hook on medium-low speed for 5-6 minutes.
04 - Place dough in a lightly greased bowl, turning to coat all sides. Cover with plastic wrap or a clean towel and let rise in a warm, draft-free place until doubled in volume, approximately 1 hour.
05 - Combine granulated sugar and lemon zest in a small bowl. Rub together with your fingertips to release the citrus oils until mixture is fragrant and well combined.
06 - Punch down risen dough gently. Roll out on a floured surface to a 12x16-inch rectangle, maintaining even thickness throughout.
07 - Spread softened butter evenly over the rolled dough. Sprinkle lemon sugar mixture over butter, then scatter blueberries across the surface.
08 - Starting from one long edge, roll dough tightly into a log. Using a sharp knife or unflavored dental floss, slice the log into 12 even pieces, approximately 1 1/4 inches wide.
09 - Arrange rolls cut-side up in a greased 9x13-inch baking dish, spacing evenly. Cover and let rise in a warm place for 45 minutes until puffy and nearly doubled.
10 - Preheat oven to 350°F during the final 15 minutes of the second rise.
11 - Bake rolls for 22-25 minutes until golden brown on top and cooked through. Internal temperature should reach 190°F when tested with an instant-read thermometer.
12 - While rolls bake, whisk together powdered sugar, milk, and vanilla extract in a medium bowl until completely smooth and lump-free. Adjust consistency with additional milk if too thick.
13 - Drizzle warm vanilla icing generously over rolls immediately after removing from oven. Serve warm for best texture and flavor.