1. Heat 2 tbs oil in a large saucepan over medium-high heat. Season chicken and cook, turning, for 6-7 minutes until golden.
2. Remove and set aside. Add onion, fennel and garlic. Reduce heat to medium-low. Cook, stirring, for 6 minutes or until soft. Add fennel seeds and bay, and cook, stirring, for 2 minutes or until fragrant.
3. Add the tomato and stock, and increase heat to high. Bring to the boil, then return chicken to pan with parmesan rind and half the marjoram.
4. Reduce heat to medium and cook, stirring occasionally, for 1 hour 15 minutes or until thickened
5. Heat remaining 2 tbs oil in a frypan over medium heat. Add sourdough and cook, stirring, for 4 minutes or until golden. Stir through grated parmesan and chopped fennel fronds. Season. Remove from heat.
6. Serve the soup with sourdough crumbs, burrata and reserved marjoram leaves.