1. Place the chicken in a heavy - based saucepan and pour over the chicken stock. The chicken should be completely covered (top up with a little water if it isn't).
2. Add the bay leaf and thyme and season lightly with salt and pepper.
3. Bring to a gentle simmer over medium heat, then reduce the heat to hold at a very gentle simmer for 30 minutes.
4. Take off the heat and leave the chicken to cool in the stock for 30 minutes.
5. Remove chicken (reserve the stock) and shred the meat, discarding the skin and bones. Set aside.
6. While the chicken is cooling, cut the corn kernels from the cob. Tear the kale leaves into bite-sized pieces and roughly chop the stalks.
7. Heat the olive oil in a large heavy-based saucepan over medium heat. Add the leek and kale stalks, season with salt and pepper and cook for 5 minutes or until softened.
8. Add corn kernels and cook for 2 minutes, then add kale leaves.
9. Strain the reserved chicken stock and pour over the vegetables, then add pasta and bring to the boil over high heat.
10. Reduce the heat to low-medium and simmer for 10 minutes or until pasta is al dente.
11. Add the shredded chicken and tarragon, increase the heat to medium - high and return to the boil.
12. Taste and adjust the seasoning, if required. Ladle into serving bowls and serve.
