Place vegetable spaghetti in a large pan of water and bring to the boil. Reduce the heat, cover the pan and simmer for 40 minutes.
Place chicken breast in a steamer and steam for 15 to 20 minutes until cooked through. Cover loosely in foil to stay warm.
Combine basil, garlic, olive oil, lemon juice, pine nuts and seasoning in a food processor and process just enough to retain texture.
When pumpkin is cool enough to handle, cut in half and scoop out the seeds. Use a fork to thread out the spaghetti-like flesh.
Shred chicken. Combine the pesto through the chicken and vegie spaghetti and serve.