In a small bowl, combine warm milk, yeast, and 1 tablespoon of the sugar. Let sit 5–10 minutes until foamy.
Combine in the bowl of a stand mixer, the flour, remaining sugar, salt, cinnamon, lemon zest, and dried blueberries. Mix to combine. Add the eggs, melted butter, and foamed yeast mixture. Mix until a soft dough forms. Knead for 8–10 minutes (by hand or mixer) until smooth and elastic.
Place dough in a lightly greased bowl, cover, and let rise until doubled in size, about 1–1½ hours.
Divide dough into 12 equal pieces. Shape into smooth balls and place in a parchment-lined 9×13-inch baking dish. Cover and let rise again for 45–60 minutes until puffy.
For the crosses, mix flour, oil, and water to form a thick paste. Transfer to a piping bag and pipe crosses over each bun.
Bake at 375°F (190°C) for 20–25 minutes, until golden brown.
For the icing, whisk icing sugar with lemon juice until smooth. Brush or drizzle over warm buns. Let the icing set before serving.