1Preheat your oven to 375°F (190°C).
Peel and thinly slice the potatoes.
Peel and thinly slice the onion.
Mince the garlic cloves.
In a large oven-safe skillet, heat the olive oil over medium heat.
Add the sliced potatoes and cook for about 10 minutes, stirring occasionally, until they start to soften.
Add the sliced onion and minced garlic to the skillet and cook for another 5 minutes, until the onion is translucent.
In a large bowl, whisk together the eggs, milk, salt, and black pepper.
Pour the egg mixture over the potatoes and onions in the skillet.
Cook on the stovetop for about 5 minutes, until the edges start to set.
Transfer the skillet to the preheated oven and bake for 15-20 minutes, until the frittata is fully set and golden brown on top.
Remove from the oven and let it cool for a few minutes before slicing and serving.