Preheat the oven to 200C (400F). Place the shelf in middle of the oven.
Brush a shallow baking tin (mine was aprox. 20x28cm / 8x11in) with a little of the melted butter. Place one sheet of phyllo over the base, letting the edges overhang. Continue layering the phyllo sheets over each other, brushing liberally with melted butter between each addition. Keep any unused phyllo sheets covered as you work - they dry out fast.
Cover the middle of the tart with foil and place on a heavy baking sheet. Bake for 8 minutes, until the edges are golden. Remove the foil and bake for a further 5 minutes.
While the base is baking, put the ricotta and eggs in a bowl and use a balloon whisk to combine. Add the blue cheese and grated Parmesan and mix together. Season with salt and pepper and stir in the mint. Pour the filling into the tart.
Bring a large saucepan of water to the boil and add a pinch of salt. Add the vegetables and cook for 2-3 minutes until a little tender. Plunge them into cold water and pat dry. Slice the leek into thin strips.
Arrange the vegetables over the custard in a nice pattern and sprinkle with the seeds. Grate some more Parmesan over the top and drizzle with a little olive oil. Bake for 20-25 minutes, or until the custard is set. You might need to add a bit of foil to protect the edges of the tart as the phyllo can colour too much.
Leave the tart to cool on a wire rack before serving.