In a pan, combine potatoes, unpeeled, and enough water to cover. Bring to the boil over a high heat. Reduce heat to medium-low, cover and boil for 15 minutes, or until just tender when pierced with the tip of a small pointed knife. Drain and set aside to cool.
Peel and coarsely grate potatoes. Sprinkle with salt and pepper.
Spray a large non-stick frying pan with vegetable oil cooking spray. Place half the potatoes in the pan in an even layer. Top with Cheddar cheese, bacon and spring onions. Cover with remaining potatoes in an even layer.
Place frying pan over a high heat and cook for 5 minutes, shaking pan gently while in contact with heat, to loosen potato cake. Using an egg slice, lift edges to see when potatoes form a golden crust.
Place a plate over frying pan and turn potatoes over onto plate. Spray pan with more vegetable oil cooking spray. Slide potatoes back into pan, cooked side up. Cook until golden underneath, about 5 minutes. Slide potao cake onto a plate, cut into wedges. Serve .