All ingredients ready? Let's begin!
Place the potatoes in a pot and cover them with water. Add a teaspoon of salt to the water. Turn the heat to high. Once the water comes to a full boil, blanch for just 2 minutes. Drain the potatoes in a colander and set them aside to cool and dry.
In a large ovenproof sauté pan or cast-iron skillet over medium heat, warm the olive oil. When the oil is hot, add the onions and garlic. Season with salt and pepper. Cook until the onions are caramelized, about 10 to 15 minutes. Transfer the onions to a bowl.
Preheat the oven to 400°F.
Place the pan back on the heat and add the stick of butter. When the butter has melted, cover the bottom of the pan with ⅓ of the potatoes.
Cover the potatoes with ½ of the onions and garlic. Season with salt and pepper. Cover the onions with ⅓ of the potatoes and then the rest of the onions. Season again with salt and pepper. Place a final layer of potatoes on top of the onions.
Place the pan in the hot oven and bake until the potatoes are cooked through and tender, approximately 15 minutes.
Using a spatula, lift the potatoes and slide them onto a serving platter. Garnish with parsley.
Serve with your favorite protein and a green salad.