Crock Pot Sour Cream and Chive Mashed Potatoes

Ingredients (8)

• 5 pounds russet Idaho® potatoes, scrubbed and peeled
• 3 cups milk, divided
• 1 1/2 teaspoons salt, plus more to taste
• Fresh ground black pepper
• 1/2 cup butter
• 1 - 1 1/2 cups sour cream
• 1/4 cup chopped chives, plus more for serving.
• Additional melted butter, for serving