Preheat oven to 200oC. Lightly grease a rectangular baking dish (26 x 16cm).
Place washed red capsicum pieces on a baking tray and bake for 20-30 minutes or until skins are browning.
Peel and slice the sweet potato into 3mm thick pieces. Line another baking tray with baking paper and place sweet potato on top of tray. Spray with olive oil spray and place rosemary sprigs on top of sweet potato. Bake for 30 minutes, or until sweet potato is soft.
Remove capsicum from the oven and allow to cool slightly. Removed browned skin from capsicum pieces.
Remove sweet potato from the oven.
Layer sweet potato over the base of the baking dish. Top with a layer of red capsicum. Repeat until all red capsicum and sweet potato used.
In a medium bowl, beat eggs, Vitasoy Soy Milky Lite, parmesan cheese, spring onion and pepper until well combined.
Pour egg mixture over the layered vegetables, rotating dish to ensure egg mixture seeps between the layers of vegetables.
Bake in pre-heated oven for 40-45 minutes or until frittata is golden brown on top and firm in the centre to touch.