Heat the oven to 190C/170C fan/gas 5. Tip the sweet potato slices, onion and courgette into a medium non-stick baking dish (ours was 18cm x 30cm x 4cm), drizzle with the olive oil, season and mix everything together. Bake for 30 mins, tossing the veg halfway. The sweet potatoes should be tender, the courgette a little charred and the onion softened.

Meanwhile, whisk the eggs and the crème fraîche together along with a pinch of seasoning. Pour the beaten egg mixture over the sweet potato, onion and courgette. Sprinkle over the manchego and put back in the oven for 25-30 mins until the tortilla is just set. Sprinkle over the chives and eat hot or cold with salad.