Cook the bacon in the air-fryer, or however you prefer to cook it, on 400°F/200°C, for 9 to 10 minutes until browned and crisp. Drain on paper towel then chop & set aside.
Toss the potato with olive oil, salt and pepper in a large bowl. Add to an air-fryer and scatter into a single layer if possible. I have an air-fryer with two smaller drawers and I use both of them for this recipe. Cook for 20 minutes at 400°F/200°C shaking once or twice during cooking, or until golden brown and softened. When cooked set potato aside. Or cook the potato in 400°F/200°C oven on a greased baking sheet for about 30 minutes, turning occasionally.
Preheat the oven to 350°F/180°C. Brush the base & side of an ovenproof, non-stick, 12-inch (30cm) frying pan with a little olive oil. Tumble the potato into the pan & arrange in an even layer.
Whisk the eggs, cream, nutmeg, garlic & a good pinch of salt & pepper together in a large bowl. Add the bacon, cheese and green onions, reserving some for garnish; stir to combine.
Cook for 20 to 25 minutes until the frittata has risen and the surface is puffed, golden brown & eggs have set. Let stand for 15 minutes before loosening the frittata from the pan with a spatula and sliding it out and onto a large plate. Sprinkle with extra green onions. Cut into about 10 wedges to serve. Serve with a salad leaves if desired.