1. Put the potatoes in a pan of cold salted water and bring to the boil. Once boiling, cook for 4-5 mins until nearly tender, and drain.

 

2. Meanwhile, heat the oil in an ovenproof frying pan and add the onion. Cook for about 5 minutes until softened, add the spinach and stir so it wilts.

 

3. Drain the sweet potatoes and add to the pan. 

 

4. Heat the grill to high. Pour the beaten eggs over the onion spinach and sweet potatoes in the pan, then cook on the stove top for 10 minutes to set the bottom of the frittata.

 

5. Then scatter the cheese on the top and put under the grill for a further 10 minutes or until golden and cooked through.

 

6. Cut into wedges and serve.