01 - In a large mixing bowl, combine flour, sugar, yeast, and salt until evenly distributed.
02 - Add warm milk, melted butter, and egg to the dry mixture. Mix until a sticky dough forms, ensuring all flour is incorporated.
03 - Turn dough onto a floured surface and knead for 8-10 minutes until smooth and elastic. Alternatively, use a stand mixer with dough hook for 5-6 minutes.
04 - Place dough in a greased bowl, cover with plastic wrap or damp towel, and let rise in a warm, draft-free area until doubled in volume, approximately 1 hour.
05 - While dough rises, combine granulated sugar and lemon zest in a small bowl. Rub together with fingers to release citrus oils until mixture is fragrant and infused.
06 - Roll risen dough on a floured surface into a 12x16-inch rectangle. Spread softened butter evenly over surface, leaving a small border. Sprinkle lemon sugar mixture across dough, then scatter blueberries in an even layer.
07 - Starting from one long edge, roll dough tightly into a log. Use a sharp knife or unflavored dental floss to slice crosswise into 12 equal pieces, approximately 1 1/4 inches thick.
08 - Arrange rolls cut-side up in a greased 9x13-inch baking dish, leaving space for expansion. Cover loosely and let rise for 45 minutes until puffy and nearly doubled.
09 - Preheat oven to 350°F while rolls complete their final rise.
10 - Bake for 22-25 minutes until tops are golden brown and rolls are cooked through. If edges brown too quickly, tent with foil for the last 5 minutes.
11 - While rolls bake, whisk powdered sugar, milk, and vanilla extract in a bowl until smooth and drizzling consistency is reached. Add additional milk 1 teaspoon at a time if too thick.
12 - Drizzle warm vanilla icing evenly over the rolls immediately after removing from oven. Serve warm while icing is still glossy, or let set for 10 minutes for a firmer glaze.