For an even creamier texture, warm the milk and butter before adding them to the potatoes. Feel free to adjust the amount of garlic and feta to your preference. For a milder flavor, use less garlic. For a tangier flavor, use more feta. A dollop of sour cream or Greek yogurt can also be added for extra creaminess. These mashed potatoes pair perfectly with roasted chicken, grilled lamb, or pan-seared salmon.