Preheat oven to 400°F.
Heat oil/butter in an oven-safe skillet. Add sliced potatoes, season with salt, pepper and paprika. Cook 8–10 minutes until just tender and lightly golden. Stir in leeks and cook 4–5 minutes until soft.
Whisk eggs, cream and herbs. Pour egg mixture over potatoes and leeks. Sprinkle cheese evenly on top.
Transfer to oven and bake 30-40 minutes until set in centre. Rest for 5–10 minutes. Slice and serve warm or room temp.
