Preheat oven to 180°C. Place the potatoes on an oiled baking tray, drizzle with 1 tablespoon oil, then roast for 15 minutes.
Heat remaining oil and butter in a pan over low heat. Add onion and cook for 20 minutes until soft and golden. Set aside to cool. Combine onion, carrot, peas, corn, zucchini and potato with cream, thyme and garlic. Season and set aside to cool.
Roll out pastry blocks on a lightly floured surface to 35 x 20cm rectangles. Place one sheet on a lightly-floured baking tray and spread the mixture in the centre, leaving a 2cm border. Brush edge with egg, place other sheet on top and press together, pinching until sealed. (We used a little extra pastry to make decorative leaves.)
Brush all over with egg. Make 2 air holes in the top and bake for 25 minutes until crisp and golden.
Hints and Tips:
Add you're favourite mash as an accompaniment.
More vegetables can be added such as broccoli, capsicum, mushroom etc.
Instead of adding pasty to top and bottom to create the pie, this mixture can be added into a baking dish, the roll of pastry can be added on top and seal around the baking dish.