In a large ovenproof non-stick or cast-iron skillet, heat 4 tablespoons oil over medium to medium-high heat.

Add the potatoes, and season with pepper and 1/2 teaspoon salt, or to taste. Cook, stirring occasionally, for 10 minutes.

Add onions, garlic, mushrooms, and continue cooking, stirring from time to time, another 10 minutes or so, until mushrooms and onions have softened and potatoes are tender. Add the kale and cook 3-5 minutes more.

Meanwhile, preheat the oven to 450°F / 230°C (210° fan-assisted).

Transfer the potato mixture to a large bowl and let cool slightly.

In a second bowl, lightly beat together the eggs with a pinch of salt and pepper, then add to the bowl with the potato mixture.

Return the skillet to medium-high heat and once hot, add the potato and egg mixture to the pan. Sprinkle the grated parmesan over top.

Lower the heat to medium and cook, shaking the skillet occasionally, until the eggs are start to set, about 5-7 minutes. TIP: You will see the egg set around the edges of the skillet and when you shake the skillet, the egg mixture will not be quite as jiggly.

Transfer the skillet to the preheated oven and cook until the top of tortilla is just set, 3-4 minutes. Turn the heat to broil and cook until the top is beginning to lightly brown in places and the tortilla seems fully set when the pan is shaken, 2-4 minutes.

Let cool, garnish with a little parsley, then using a spatula, divide the tortilla into pieces.

Serve and enjoy!