Preheat oven to 220°C (200°C fan-forced). Heat a large heavy frying pan over medium-high heat. Add 2 tbs of the oil and half the chorizo. Cook, stirring, for 3 mins or until crisp. Using a slotted spoon, transfer the chorizo to a 23cm x 33cm baking dish. Season the chicken well with salt and pepper. Add half the chicken to the frying pan and cook, turning once, for 6 mins or until golden brown all over. Transfer to the baking dish. Repeat with the remaining chicken.
Pour off all but 2 tsp of the oil from the frying pan. Add the pumpkin, swede, carrot, garlic and thyme to the pan. Cook for 6 mins or until the vegetables are caramelised and beginning to soften. Add the stock and bring to a simmer. Pour the mixture into the baking dish.
In a small bowl, mix breadcrumbs, pepitas, remaining 1 tbs of the oil and remaining chorizo. Sprinkle the breadcrumb mixture over the chicken and vegetables in the baking dish.
Bake for 20 mins or until the mixture is bubbling and breadcrumb topping is crisp and golden brown. Set aside for 5 mins to cool slightly. Sprinkle with parsley and extra thyme.