Preheat the oven to 180°C conventional oven/ 160°C fan-forced (350° Fahrenheit/Gas 4). Grease a round pie dish with butter (alternatively, line a baking dish with baking paper).
To prepare the artichokes: Pour the lemon juice into a large bowl of water – this is to prevent discolouration of the artichokes. Use disposable gloves when handling the artichokes. Wash the artichokes under cold running water and drain. Snap off all the tough outer artichoke leaves. Continue to snap of leaves around the artichoke until you reach the leaves that are almost completely yellow and feel softer than the outer ones. Cut the artichoke stem to 3cm in length from the base. Trim off the outer skin from around the base of the artichoke and the stem. Cut 2-3 cm off the top of the artichoke. Cut the artichoke in half and use a teaspoon to scoop out and discard the furry choke near the base of the leaves. Cut each artichoke half into 4, then immediately place in the bowl of water with lemon juice. Repeat with the remaining artichokes.
Drain the artichokes and cook together with potatoes in a large saucepan of salted boiling water, for 7 minutes. The potatoes should be cooked but firm. Drain and set aside.
Heat the butter in a frying pan over low heat. Cook the red onion until soft and caramelised (approximately 8 minutes). Transfer the potatoes and artichokes to the frying pan and toss until lightly browned (approximately 4-5 minutes). Season with salt and pepper to taste, then set aside to cool slightly.
Use a fork to whisk the eggs, Parmigiano Reggiano and parsley in a medium-sized bowl. Add a drizzle of extra virgin olive oil and season well with salt and pepper. Arrange the artichokes, cut side down on the base of the pie dish. Spoon the onion and potato mixture in between the artichokes. Pour the egg mixture evenly over the onion, artichoke and potato mixture. Bake the frittata for 25 minutes.
Allow the frittata of artichokes to cool for 5 minutes before serving – buon appetito.
6 artichokes|Juice of 1 lemon|40g unsalted butter|1 red onion, cut in half and thinly sliced|1 potato, peeled, halved and sliced thinly |6 eggs|40g Parmigiano Reggiano, finely grated|1 tablespoon flat-leaf parsley, finely chopped|Extra virgin olive oil|Sea salt, freshly ground black pepper