Wash, peel, and slice the potatoes into thick rounds. Heat the oil in a pan over high heat, reserving 1 tablespoon of oil. Fry the potato slices for about 15 minutes, stirring regularly.
Place the cooked potatoes on paper towels to remove excess oil. Season with salt and pepper.
Wash the bell pepper, cut it in half, remove the stem, seeds, and white ribs, then slice the flesh into strips. Sauté the bell pepper in 1 tablespoon of oil with a bit of salt for 5 minutes over high heat.
In a bowl, beat the eggs with the heavy cream. Add the potatoes, bell pepper strips, salt, and pepper, and mix well.
Heat the butter in a high-sided non-stick pan. Pour in the egg mixture. Preheat the oven to 356°F and bake for 25 minutes.
Garnish the frittata with chopped parsley leaves.