Set oven to 375 degrees (set oven rack to second-lowest position).
Butter a 13 x 9-inch baking dish.
Heat oil and butter in a skillet; add in frozen shredded potatoes, both onions, cayenne pepper (if using) 1 teaspoon seasoned salt and black pepper to taste; cook for about 8-10 minutes or until just very lightly browned.
Add in ham and cook for 3 minutes more, mixing occasionally with a wooden spoon or spatula; transfer the mixture to the prepared baking dish.
In a bowl whisk together the eggs with whipping cream, Italian seasoning and 1 teaspoon seasoned salt then pour the egg mixture into the baking dish; toss with the potatoes.
Bake for 20-22 minutes.
Remove from oven and sprinkle with about 2 cups grated cheddar cheese; return to oven uncovered for another 5-8 minutes until the cheese is melted and eggs are set.