Pre-heat the oven to 180°C. Line an 8 inch springform square cake tin with nonstick baking paper on the base.
Heat the olive oil in a casserole dish over a medium heat until hot. Sweat the onion and potato for 8-10 minutes, stirring occasionally until softened. Add the chorizo and continue to cook for 3-4 minutes.
Meanwhile, whisk together the eggs, milk and seasoning in a bowl. Spoon the potato mixture into the base of the cake tin, then sprinkle over the chopped olives. Pour over the egg mixture.
Bake for 15-20 minutes until the egg is set and coloured on top. Remove once set and coloured and leave to stand in the tin for 5 minutes. Turn out from the cake tin when you are ready to serve.
Cut into square potions and arrange on serving plates. Garnish with a few pea shoots before serving.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.