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 and view the full Food safety at home video.