Preheat oven to 200°C / 180°C fan-forced. Line an oven tray with foil. Spoon tomato passata over base of a 20cm -(8 cup capacity) heavy based ovenproof fry pan

Whisk ricotta, sour cream and egg in a jug. Season with salt and pepper as desired

Top tomato passata in pan with 1½ lasagne sheets, tearing if necessary, to cover base of pan. Spoon over ¾ cup of the Basic Bolognese sauce, then dollop with about 3 tbsps. of the ricotta mixture. Sprinkle with ½ cup of mozzarella. Repeat with another 2 layers of ingredients, ending with lasagne sheets. Spread the top evenly with remaining ricotta mixture and sprinkle evenly with remaining mozzarella

Bake on prepared oven tray for 30 minutes or until golden brown and bubbling (cover loosely with foil if over-browning). Remove from oven. Allow to stand for about 10 minutes, before serving as this helps make the lasagne easier to cut into portions