Preheat the oven to 180°C.

Peel and finely chop the onion. Peel and dice the sweet potato.

Heat the olive oil in a pan over medium heat. Sauté the diced sweet potatoes and onion for about 15 minutes, stirring regularly. Add the spinach leaves.

In a bowl, break the eggs and season them.

Whip them into an omelette and pour them into a 20 cm diameter springform pan. Add your preparation as well as the cooking oil.

Bake for about 12 minutes until the omelet is set. Take out of the oven and let cool.

Serve the frittata warm or at room temperature.