Step 1

Finely chop the fennel. Reserve 2 tablespoons of the feathery fronds to serve.

Step 2

Heat 1½ tablespoons of the oil in a large frying pan over medium heat; cook fennel, garlic, shallots and ground fennel, stirring, for 8 minutes or until lightly golden. Transfer mixture to a large bowl; stir in rind. Season to taste.

Step 3

Wash spinach leaves but don't dry. Cook spinach in same pan over high heat, in two batches, until wilted; drain. When cool enough to handle, squeeze out excess liquid. Coarsely chop spinach; stir into fennel mixture. Season to taste. Refrigerate until cooled. Stir in peas.

Step 4

Preheat oven to 200°C/400°F.

Step 5

Combine tomatoes, basil and remaining oil in a bowl; season.

Step 6

Make ricotta béchamel. Whisk ricotta, eggs, yoghurt, juice and feta in a large bowl until combined. Whisk mineral water into mixture until combined.

Step 7

Spread one-third of the tomato mixture over the base of a 3-litre (12-cup) baking dish. Cover with one-third of the pasta sheets. Top with half the spinach mixture and half the béchamel. Continue layering with remaining pasta sheets, tomato mixture, spinach mixture and béchamel, finishing with pasta sheets and tomato mixture. Top with spoonfuls of ricotta.

Step 8

Bake lasagne for 45 minutes or until top is golden and pasta is cooked (cover with greased foil if necessary to prevent overbrowning). Stand for 10 minutes before serving. Serve lasagne drizzled with extra oil and topped with extra basil and reserved fennel fronds.