01 -
Set the oven to 200°C to preheat.
02 -
Place the potato in a medium pot and cover with at least 2.5 cm of water. Bring to a boil over medium-high heat and cook until fork-tender, approximately 22 to 25 minutes.
03 -
Drain the potato, allow it to cool slightly, then cut into thin rounds. Set aside.
04 -
Heat olive oil in a small, oven-safe skillet over medium heat. Add sliced onion and zucchini, season with salt and pepper, and sauté until vegetables are tender, about 4 minutes.
05 -
Add the potato slices to the skillet and sauté until all vegetables are lightly browned, 5 to 7 minutes. Arrange the mixture in an even layer in the pan and remove from heat.
06 -
Whisk the eggs until smooth, then pour evenly over the vegetables in the skillet. Scatter grated Manchego cheese on top.
07 -
Transfer the skillet to the oven and bake until eggs are fully set and the top is golden brown, 12 to 15 minutes.
08 -
Allow to cool slightly and serve warm or at room temperature, accompanied by a fresh side salad if desired.