Thoroughly wash potatoes and dice into small ½-inch cubes. Place the potatoes into a pot with salted water (enough to submerge the potatoes). Bring to a boil and parboil for 7-8 minutes until cooked but still slightly firm. Drain the potatoes and add in olive oil, spices, and salt and stir to coat.
While the potatoes are cooking dice the onions and bell peppers and in a large cast iron add a tablespoon of olive oil. Bring to a high heat and then add in the onions and pepper. Cook until slightly translucent and golden brown for about 10 minutes.
Remove the peppers and onions from skillet. Add in one more tablespoon of olive oil and add in the parboiled potatoes. Cook the potatoes until they are crispy on all edges. This should take around 10 minutes while flipping potatoes every few minutes.
When potatoes are cooked and crispy add in the cooked bell pepper and onion. Stir to mix everything thoroughly. Keep in the large cast iron skillet or transfer home fries to smaller individual oven-safe ramekins. First place mixture of cheddar and mozzarella then home fries and then sprinkle more cheese on top.
Place the ramekins on a baking tray and put in the oven on a LOW broil and broil for 3-6 minutes until cheese is melted and starting to bubble.
Serve while home fries are still hot and cheese is melted. Optionally, garnish with green onions, and serve with sour cream.
Enjoy!