1. Whisk together sourdough starter, milk, egg, sugar, and softened butter in a large bowl.

2. Add flour and salt, mix until no dry bits remain and dough is sticky.

3. Cover dough and rest for 30–45 minutes for autolyse.

4. Knead dough for 5–8 minutes until smooth and elastic.

5. Place dough in an oiled bowl, cover, and bulk ferment 4–6 hours until doubled.

6. Combine butter, brown sugar, and cinnamon to make the filling.

7. Roll dough into a 12×16 inch rectangle on a floured surface.

8. Spread cinnamon filling evenly, leaving a 1 inch border.

9. Roll dough into a log, cut into 12 pieces.

10. Shape each piece into a bunny by creating ears and a face coil.

11. Proof shaped bunnies 2–3 hours at room temperature or refrigerate overnight.

12. Preheat oven to 375°F (190°C) and line a baking tray.

13. Brush rolls with milk or egg wash and bake 20–25 minutes until golden.

14. Whisk powdered sugar, milk, and vanilla until smooth and drizzle over warm rolls.

15. Cool on a wire rack 10–15 minutes before serving.