Cook the Potatoes:

1. Boil the Potatoes: Place the cubed potatoes in a large pot of salted water. Bring to a boil and cook until the potatoes are tender when pierced with a fork, about 15-20 minutes.
2. Drain and Mash: Drain the cooked potatoes and return them to the pot. Mash them using a potato masher or ricer until smooth and free of lumps.

Prepare the Potato Mixture:

3. Add Butter and Cream: To the mashed potatoes, add the softened butter and heavy cream. Mix well until fully combined and the potatoes are smooth and creamy.
4. Mix in Egg Yolks: Stir in the egg yolks, garlic powder, onion powder, salt, and pepper. The egg yolks help make the mixture richer and smoother, while the seasonings add flavor.

Pipe the Potatoes:

5. Preheat the Oven: Preheat your oven to 400°F (200°C). Grease a baking sheet with olive oil or line it with parchment paper.
6. Pipe the Potatoes: Transfer the mashed potato mixture to a piping bag fitted with a large star tip. Pipe the potatoes into swirls or rosettes on the prepared baking sheet. Aim for about 12-15 swirls, depending on the size you prefer.

Bake the Potatoes:

7. Bake in the Oven: Place the piped potatoes in the oven and bake for 25-30 minutes, or until the edges are golden brown and crispy.
8. Serve: Once baked, remove the Duchess Potatoes from the oven and transfer them to a serving platter. Garnish with fresh parsley or chives, if desired.