Peel and cut the fresh U.S. Russet potatoes into small cubes. Boil in boiling water for 10 - 15 mins depending on size.
In a non-stick saucepan, sauté spinach, onion, red capsicum and boiled potatoes in butter, and season with a pinch of salt and black pepper over medium heat. Set aside.
In a large bowl, combine egg, parmesan cheese, milk and seasonings. Stir to mix.
Add in the sautéed vegetables to the large bowl. Stir to mix.
Pour the mixture into a greased 10-inch pan over medium heat. Stir lightly with a fork until almost set. Cover for 3-4 mins on medium heat to allow mixture to cook through.
Remove from heat and serve.