Preheat oven to 160°C/fan 140°C/gas 3 and line a 20cm square baking tin with baking paper.

Add sweet potatoes to a saucepan of cold salted water and bring to a boil. Simmer for 8-10 minutes until tender. Drain and set aside.

At the same time place spinach in a bowl, cover with boiling water and set aside for a few minutes. Drain and once cool roughly chop.

Arrange cooked sweet potato, spinach, half the tomatoes and half the feta in prepared tin.

Whisk together eggs, milk and parmesan and season with salt and pepper.

Pour mixture over vegetables and scatter over remaining tomatoes and feta. Add spoonfuls of pesto and bake for 40-45 minutes until golden and egg is set. 

Divide between plates and serve warm or cold. 

Can be stored refrigerated in an airtight container for 3 days.