Begin by preparing your potatoes. Wash and pat dry. Then use a sharp knife to quarter. The reason we like to quarter our potatoes is so that they boil faster.
Place potatoes into a large pot and fully submerge them with water. Add the kosher salt to the pot and stir until the salt is dissolves.
Heat over high heat and bring to a boil. Turn the heat to medium and let the water gently boil for around 20-25 minutes or until the potatoes are tender and you can easily pierce the potatoes with a fork.
Preheat the oven to broil and spray a 9x13-inch casserole dish with non-stick cooking spray. Set aside.
Drain potatoes from the liquid and then place them back in the pot. Add the butter and cream cheese to the potatoes. Use a hand mixer or potato masher to mash potatoes and incorporate the butter and cream cheese into the potatoes.
Add the Greek yogurt (or sour cream), garlic powder, and salt to the potatoes and mix until incorporated.
Slowly add in the heavy cream to the potatoes while mixing. Mix until creamy.
Finally, add in the romano cheese and cheddar cheese to the potatoes and mix until the cheese is melted and incorporated.
Add all of the potatoes to the casserole dish and sprinkle with any romano cheese and cheddar cheese.
Place the potatoes in the oven and broil for 5-6 minutes or until the cheese turns golden brown.
Remove from the oven and sprinkle with chopped parsley and pepper. You have the option to add a few pats of butter to the top of the potatoes once they are broiled.