Preheat the oven to 400.
Fill a large pot with water and place on the stove. Bring the water to a boil.
While the water is heating, thinly slice your potatoes and onion.
When the water comes to a boil, add the potatoes and cook for 5 minute.
Meanwhile, heat a medium cast iron or oven-safe skillet over medium heat. Add the olive oil and onions to the pan. Stir the onions and cook until translucent.
Drain the potatoes and move them to the pan. Add the chopped olives, salt and smoked paprika and stir everything to combine.
In a large bowl whisk the eggs, milk, and cheese together then pour the mixture into the pan.
Gently shake the pan to help the eggs settle between the potato mixture and continue to cook over medium heat until the eggs just start to set on the edges of the pan.
Place the pan in the oven and bake for 15-20 minutes or until the top of your frittata has puffed up and turned golden.
Remove from the oven and allow to cool 10 minutes before slicing and serving.