• 6 tablespoons unsalted butter, divided use.
• 4 cups (1/2-inch diced) russet potatoes, peeled.
• 1 small sweet onion, small diced.
• ½ teaspoon kosher salt.
• ½ teaspoon black pepper.
• 4 cups chopped cooked corned beef.
• ½ teaspoon garlic powder.
• ½ teaspoon onion powder.