Preheat the oven to 200C (Gas mark 6)
Finely slice the fennel.
Slice the leeks horizontally to roughly match the size of the leeks
Chop the cherry tomatoes in half.
Chop the olives into slices.
In a good oven proof dish drizzle a layer of olive oil, then layer in the fennel & leeks.
Sort of smush the oil all over the leeks & fennel
Sprinkle the herbs over evenly
Dot the olives & tomatoes around the dish. Then sprinkle the seeds (or nuts if using) over the top
Drizzle a little more olive oil over and season to taste.
Put in the oven for around 30 minutes, or until the leeks are softened and the edges are all lovely and caramelised.