Preheat your oven to 425°F (220°C). Prepare a baking sheet lined with parchment paper.

Peel and chop the Yukon Gold potatoes into even chunks, then place them in a large pot of salted water. Boil until tender, about 15-20 minutes. Drain thoroughly.

Melt 4 tablespoons of unsalted butter in a medium saucepan over medium heat. Add the minced garlic and sauté until golden and fragrant, about 1-2 minutes. Stir in 3 tablespoons of half and half and set aside.

Transfer the drained potatoes to a large mixing bowl and mash until smooth and fluffy.

Add the sautéed garlic-butter blend and Parmesan cheese to the potatoes. Season with salt and pepper. Beat in the egg yolks one at a time until fully blended.

Transfer the potato mixture into a piping bag fitted with a star nozzle or spoon generous mounds onto the baking sheet.

Melt additional butter and brush over the piped shapes. Bake for about 16-19 minutes until tops are golden and crisp.

Allow to cool slightly, then serve warm, garnished with parsley or additional Parmesan if desired.