Extra time:25min cooling ›
- Heat 1 tablespoon olive oil in a saucepan over medium heat. Add garlic and chilli flakes; cook and stir until golden, about 1 minute. Stir in basil and oregano; cook until fragrant, about 1 minute. Stir in tomato passata. Simmer sauce until flavours combine, about 20 minutes.
- Combine spinach and 2 tablespoons water in a large pan over medium heat. Cover and cook until spinach is wilted, 3 to 5 minutes. Drain and cool until easily handled, about 5 minutes. Gather spinach into a ball and squeeze out excess water. Chop coarsely.
- Combine chopped spinach, ricotta and 40g Parmesan cheese in a bowl.
- Preheat oven to 200 C / Gas 6. Line 2 baking trays with baking parchment.
- Divide aubergine, red pepper and orange pepper between the two lined baking trays. Drizzle with 2 tablespoons olive oil and toss to coat. Season with salt and pepper.
- Roast in the preheated oven, stirring every 10 minutes, until tender and browned in spots, about 30 minutes. Remove from oven.
- Bring 1.4 litres water to the boil; add salt. Pour in instant polenta in a steady stream, whisking constantly. Reduce heat to low. Whisk until polenta thickens, about 5 minutes. Cover and cook, stirring vigorously every 10 minutes, until polenta is the consistency of porridge, about 30 minutes.
- Reduce oven temperature to 180 C / Gas 4. Lightly grease a lasagne baking dish.
- Spread half the polenta evenly in the bottom of the baking dish. Layer half of the spinach mixture, roasted vegetables and sauce on top. Top with some of the grated mozzarella and Parmesan cheese. Repeat layers with remaining polenta, spinach mixture, roasted vegetables and sauce. Top with remaining grated mozzarella and Parmesan cheese.
- Bake in the preheated oven until cheese melts and sauce is bubbly, about 20 minutes. Let cool before cutting so that the layers hold, at least 20 minutes.
The filling, sauce and roasted vegetables can be made ahead of time and refrigerated. Bring to room temperature before assembling. The polenta needs to be cooked just before assembly because it firms up when it cools and cannot be spread.
Parmesan cheese is not truly vegetarian, as it contains animal rennet. To make this dish 100% vegetarian, omit the cheese or find a suitable vegetarian substitute made without animal rennet. In supermarkets look for the 'parmesan style hard cheeses' which are suitable for vegetarians.