- Preheat oven to 220C.
- Melt 20g of butter in a large saucepan over high heat. Separate the leaves and stalks of the silverbeet and chop. Cook stalks, onions and garlic for 5 minutes or until tender. Add the leaves and cook for 3-5 minutes or until wilted. Set aside.
- Melt the remaining butter in a saucepan over medium heat. Add the flour and cook for 1 minute. Gradually add the milk and cook, whisking, for 5-7 minutes or until thickened. Remove from the heat and stir through 1/4 of a cup of parmesan and lemon rind.
- Add to the silverbeet mixture and mix well to combine. Spoon into an 8 cup-capacity ovenproof dish. Toss the bread with the remaining parmesan and sprinkle over the silverbeet.
- Drizzle with olive oil and bake for 15 minutes or until golden and crisp.