Activate the Yeast
In a bowl, combine warm milk, sugar, and yeast.
Let sit for 5–10 minutes until foamy.
Make the Dough
Add egg, softened butter, and salt.
Gradually mix in flour until a soft dough forms.
Knead for 8–10 minutes by hand or 5–6 minutes with a dough hook until smooth and elastic.
Place in a greased bowl, cover, and let rise 1–1½ hours until doubled.
Prepare the Filling
In a small bowl, mix sugar, cornstarch, and lemon zest.
Set blueberries aside.
Assemble the Rolls
Roll dough into a 12x18-inch rectangle.
Spread softened butter evenly over dough.
Sprinkle lemon sugar mixture evenly.
Scatter blueberries across surface.
Roll tightly from the long side.
Slice into 12 rolls and place in a greased 9x13-inch baking dish.
Second Rise
Cover and let rise 30–45 minutes until puffy.
Bake
Preheat oven to 350°F (175°C).
Bake for 25–30 minutes, until tops are lightly golden and centers are cooked through (internal temperature about 190°F).
Glaze
Whisk powdered sugar, lemon juice, and zest.
Drizzle over warm rolls before serving.