Preheat your oven to 400°F (200°C). Peel the russet potatoes and cut them into thin slices using a mandoline slicer.
In a large oven-safe skillet, heat 2 tablespoons of olive oil over medium heat. Arrange the potato slices in a circular pattern and cook for 10-12 minutes until golden and slightly crispy.
Crack the eggs into a mixing bowl, add 1 tablespoon of water, and whisk until well combined and slightly frothy.
Add the roughly chopped spinach and crumbled cheese to the eggs and gently fold them together until coated.
Pour the egg and spinach mixture over the potato crust in the skillet and gently press down with a spatula. Drizzle the remaining olive oil on top.
Bake in the oven for 20-25 minutes until the eggs are set and the top is lightly golden. Check for doneness by inserting a toothpick.
Remove from the oven, let cool for a few minutes, slice into wedges, and serve warm.
