Heat oven to 200C/180C fan/gas 6. Put the breadcrumbs, olives, parsley, mint, lemon zest, anchovies and garlic in a food processor, and blitz until everything is roughly chopped. Tip into a bowl and stir through the pine nuts, sultanas, chilli flakes (if using) and a good grinding of black pepper. Arrange the fennel slices in a small roasting dish and drizzle with a little olive oil

Working methodically, lay each fish fillet, skin-side down, on your work surface, cover with some of the crumb mixture, then drizzle ½ tsp olive oil over each. Roll up the fillets, leaving the tails sticking up. Use a cocktail stick to secure, then stuff a little more of the crumb mixture into the sides.

Arrange the rolled-up sardines on the fennel, scatter over the remaining crumb mixture, then pop the slices of lemon and bay leaves in the gaps. Drizzle with the remaining olive oil and season with sea salt and pepper. Bake in the oven for 20 mins until the fish is cooked through and the crumbs are golden and crisp in places. Serve scattered with the fennel fronds.