Preheat oven to 200C (400F) and place a baking tray on the middle shelf.

Line a 20cm (8in) springform pan with baking paper & grease generously with olive oil. Or grease a small oven-proof frying pan.

Place ingredients 1 and 2, if using in the prepared tin. Pour over the beaten egg & scatter over the highlight ingredient. Season.

Place on the preheated tray and bake until golden and puffy and the centre feels firm and springy, 10-15 minutes.