Creamy Garlic Mashed Potatoes: My Secret's Out!

Ingredients

• 1 head of garlic (about 2 inches diameter)
• 1 tablespoon olive oil (15 ml)
• Pinch of salt
• Pinch of black pepper
• 2 pounds Yukon Gold potatoes, peeled and quartered (approx. 900g)
• 1 teaspoon salt, plus more to taste
• ½ cup milk (120 ml)
• 4 tablespoons unsalted butter, softened (57g)
• ¼ cup sour cream or crème fraîche (60 ml)
• Freshly ground black pepper, to taste
• 2 tablespoons chopped fresh chives or parsley, for garnish (optional)