Ingredients
2 pounds russet, Yukon gold, or long white potatoes, peeled
Coarse salt and freshly ground black pepper
1 cup milk or cream
4 tablespoons unsalted butter
1 cup grated russet potato, squeezed dry to remove excess moisture
1 large egg
1 large egg yolk
1/4 cup milk
1/4 cup thinly sliced scallions
1/2 cup all-purpose flour
2 teaspoons coarse salt
1 teaspoon baking powder
1/2 teaspoon freshly ground pepper
1/4 cup unsalted butter, preferably Irish, plus more for serving
Preparation
Make the mashed potatoes: Bring a saucepan of water fitted with a steamer insert to a boil over medium-high heat. Peel and cut potatoes into 1-inch pieces; add to steamer insert. Cover and cook until fork-tender.
Heat milk and butter in a small saucepan over medium-high heat. Transfer potatoes to a large bowl; mash potatoes using a potato masher. Slowly add milk mixture and stir to incorporate with a wooden spoon until smooth; season with salt and pepper.
Make the boxty potatoes: Transfer 1 1/2 cups mashed potatoes to a large bowl; reserve extra mashed potatoes for another use. Add grated potato to bowl with mashed potatoes. Whisk together egg and egg yolk; add to bowl with potatoes along with milk and scallions and stir to combine. In a medium bowl, whisk together flour, salt, baking powder, and pepper; add to bowl with potatoes and stir to combine.
Melt 2 tablespoons butter in a large heavy-bottomed skillet over medium heat. Working in batches, adding butter as necessary, add 2 tablespoons batter to skillet and gently spread to form a 2-to-3-inch round; cook, turning, once, until browned on both sides, about 4 minutes per side. Serve immediately with butter.
