Prepare Tangzhong: Combine a portion of the bread flour and whole milk in a microwave-safe bowl, heat for 30-60 seconds until thickened.

Make Dough: Combine remaining milk, sugar, yeast, and egg in a stand mixer, then add flour, salt, butter, and tangzhong, knead until smooth.

Add Flavorings: Fold in lemon zest and poppy seeds, knead briefly until mixed.

First Proof: Let dough rise in a greased bowl covered with a cloth for about 1 hour.

Prepare Blueberry Curd: Whisk blueberry curd ingredients in a saucepan over medium heat until thickened, strain and chill.

Shape Rolls: Roll dough out, spread blueberry curd, cut into strips, and roll into pinwheels.

Second Proof: Arrange rolls in a baking pan, cover, and proof for about 30 minutes.

Bake: Preheat oven to 350°F (175°C) and bake for 20-25 minutes until golden brown.

Frosting Preparation: Beat mascarpone, lemon zest, sugar, and salt until smooth, fold in whipping cream.

Final Assembly: Frost cooled rolls with mascarpone frosting and drizzle with blueberry curd.