Can’t decide between sweet potatoes or golden for the feast? Try both in this elegant version of mashed potatoes that gets baked to a golden brown.
2 lbs Yukon gold potatoes, peeled
2 lbs sweet potatoes, peeled
3/4 cup whole milk
1 cup (2 sticks) butter, melted
3 egg yolks
Cut the Yukon potatoes and sweet potatoes into 1-inch chunks and place in a large pot. Add enough water to cover by 1 inch. Add salt. Partially cover and heat to a boil on high. Reduce heat to simmer. Cook 20–25 min., until tender.
Meanwhile, preheat oven to 425°F. Grease a 2½-qt baking dish. Drain cooked potatoes well and transfer to a large mixing bowl. Add the milk and butter. With hand mixer or stand mixer, beat potatoes until smooth. Season with salt and pepper to taste.
In a medium bowl, beat the egg yolks until smooth. Add to potatoes and beat until just incorporated. Transfer potatoes to prepared baking dish, smoothing top. With butter knife or mini offset spatula, create swirls on top.
Bake 20 min., until slightly puffy. Broil 1 min., until top is golden brown.