Mushroom, spinach and sweet potato frittata

Dice the onion and stir fry in a large skillet. When the onion is tender, add the peeled sweet potato, diced, and the mushrooms, cut into chunks.

Cook all together for 5 more minutes, stirring, and after that, add the spinach. Stir and cook until well-combined, and place the mix in a mould suitable for the oven, previously greased.

Mix the eggs, milk, salt, pepper, and thyme in a bowl, and pour it over the vegetables. Finish with mozzarella cheese on top of the frittata and bake at 190 °C for 30 minutes.