Wash potatoes. Place in pot and cover with water by about 2 inches. Add 1 Tbsp of salt.
Bring to a boil, turn heat to low, cover and cook for 20-25 minutes. Potatoes should be cooked all the way through. Pierce with sharp knife to check doneness.
Poor potatoes into colander and allow to sit and cool for 5-10 minutes.
Preheat oven to 425°.
Drizzle to baking sheets with half of the olive oil. Spread oil with basting brush.
Place potatoes onto baking sheets and use flat-bottomed mug or bowl to smash each potato to about ¼ inch thick.
Drizzle with melted butter and then remaining olive oil.
Sprinkle potatoes with garlic salt, onion powder and chives.
Bake for 30 minutes. Bake both pans at the same time, switching halfway through.
Eat hot with sour cream and chives.