Peel and dice the potatoes into uniform pieces to ensure even cooking.

Heat 2 tablespoons olive oil in an oven-safe skillet over medium heat, add the diced potatoes, and cook for about 10 minutes, stirring occasionally, until golden and tender.

Add 1 cup chopped onion and 1 cup diced bell pepper to the skillet, sauté for 5 minutes until softened.

In a mixing bowl, whisk together 6 large eggs with salt and pepper until well combined and slightly frothy.

Reduce heat to low and pour the egg mixture over the potatoes and vegetables in the skillet, cooking gently for 2 minutes to begin setting.

Sprinkle 1 cup shredded cheese evenly over the top of the egg mixture.

Cook undisturbed on low heat for 5 minutes to set the bottom before baking.

Preheat the oven to 375°F (190°C). Transfer the skillet to the oven and bake for 15–20 minutes until the edges are golden and the center is fully set.

Remove from oven and let the frittata rest for 5 minutes before slicing to help it hold its shape.