(Nutrition information is calculated using an ingredient database and should be considered an estimate.)
Heat oil in a large frying pan over medium heat. Add onion. Cook for 5 minutes or until softened. Add 1/2 cup water. Bring to the boil. Reduce heat to medium. Simmer for 10 minutes or until water is absorbed and onion is caramelised. Stir in thyme.
Preheat oven to 180C/160C fan-forced. Grease a 6cm-deep, 20cm (base) springform pan. Line base and side with baking paper.
Place potato slices in a large bowl. Add Flora. Season with salt and pepper. Toss to coat. Layer 1/4 of the potato, overlapping slightly, in prepared pan. Spread 1/3 of the caramelised onion over potato. Sprinkle with 1 tablespoon parmesan. Repeat layering with potato, caramelised onion and parmesan, finishing with a layer of potato.
Cover pan with foil. Bake for 40 minutes. Remove foil. Bake for 45 minutes or until potato is tender when a skewer is inserted into centre of cake and top is golden. Cover to keep warm. Stand in pan for 30 minutes (see notes). Carefully transfer to a serving plate. Sprinkle with extra thyme. Cut into wedges. Serve.