Start by cooking the blueberries with brown sugar, lemon juice, and water. Once thickened, stir in cornstarch to make a spreadable jam that stays juicy in the rolls.
Whisk flour and water in a small pot over medium heat until it forms a paste. Tangzhong keeps your dough soft and tender for days.
Combine flour, sugar, yeast, salt, milk, cream, egg, tangzhong, and butter. Knead until smooth and slightly tacky. Let it rise until doubled in size for that fluffy texture.
Roll out the dough into a rectangle. Spread cinnamon sugar first, then blueberry jam evenly across. Roll it tightly into a log.
Cut the log into 12 rolls and place them in the prepared pan. Bake until the centers are lightly golden and cooked through, about 30 minutes.
Beat butter and cream cheese until smooth. Mix in powdered sugar, blueberry filling, and cream for a luscious, tangy frosting.
Spread frosting over warm rolls for the ultimate gooey experience. Top with extra fresh blueberries for a gorgeous presentation.