What is better than adding cream, eggs, and cheese to your mashed potatoes? 

Adding all of the above to two kinds of potatoes!

It's the holidays, why choose?

I have no idea why these are called Duchess potatoes, but right now they are reminding me of the only part of last week's news cycle that didn't make me want to go live under my duvet, so I'll go with it.

I'd definitely consider these potatoes worthy of the title, with their light, fluffy interiors and golden shells. The egg yolk, cream, and cheese give them a richness that doesn't overwhelm. They are special, but not too showy about it. And here, mixing white and sweet potatoes adds a nice flavor and texture variation and just enough extra work to claim this as a special occasion dish.

Mixed Duchess Potatoes

Adapted from Geoffrey Zakarian

• 1 lb russet potatoes, peeled and cut into 1 inch pieces
• 1 lb sweet potatoes or yams, peeled and cut into 1 inch pieces
• kosher salt
• fresh ground black pepper
• 1/4 cup heavy cream
• 6 tbs unsalted butter + more for baking dish
• 2 egg yolks
• 1/2 cup grated parmesan
• parsley, for garnish

1. In 2 large pots, add russet and sweet potatoes (separately, one potato type to each pot) with 1/2 tsp salt in each, and add enough water to cover the potatoes. Bring to a boil over high heat, then lower to a simmer and cook until potatoes are fork tender, about 10 minutes.
2. Drain the potatoes then press each type separately through a ricer or food mill and add back to the pots (still separate). Place pots back over low heat to dry out the potatoes a bit. 
3. Heat the cream and 4 tbs of the butter in a small sauce pan over med-low heat until cream is warm and butter is melted. Stir half of this mixture into each pot, then stir one egg yolk into each pot and season with salt and pepper. Stir half of the parmesan into each.
4. Heat oven to 400 degrees and butter a baking dish (8x8 or a round pie dish will work). Melt remaining 2 tbs butter over low heat and set aside. Fill a piping bag (fitted with a star tip if desired) or a plastic, zip-top bag with a corner snipped off with the russet potato mixture and pipe into swirls into the dish. Fill the bag with the sweet potato mixture and repeat, filling in the gaps between the russet potato swirls. Brush the tops of the swirls with the melted butter, then bake 30-40 minutes. Garnish with the parsley and serve hot.