
Make the blueberry filling: In a medium pot, combine blueberries, sugar, cornstarch, lemon zest, lemon juice, and almond extract. Cook until thick like jelly. Cool completely.
Prepare the dough: In a large bowl, rub lemon zest into sugar, then mix in warm milk and yeast. Wait for it to foam, then add egg, yolk, and butter. Stir in flour and salt.
Knead the dough until smooth, then place in a greased bowl to rise until doubled in size.
Roll out the dough to a rectangle, spread with filling, roll tightly, and cut into rolls.
Place rolls in a lined pan, let rise again until puffy, then bake at 350°F until golden.
Prepare frosting and spread it on warm rolls. Serve warm.