Boxty for St. Patrick's Day

Here's another Boxty recipe, this one is from the Just-Potatoes group, by way of the Dorie's Recipe Box group:

Boxty from Ireland

1/2 pound potatoes, unpeeled
1 1/2 cups buttermilk
1/2 pound potatoes, peeled and grated
1 3/4 cups all-purpose flour
1 teaspoon baking soda
salt and ground black pepper to taste
2 tablespoons butter, or as needed

Preheat oven to 450 degrees F (230 degrees C). Scrub the unpeeled potatoes and prick them several times with a fork; place onto a baking sheet. Bake in the preheated oven until the potatoes are easily pierced with a fork, 50 minutes to 1 hour. Remove, cool, and peel. Mash the potatoes with the buttermilk. Stir in the grated raw potato, flour, baking soda, salt, and pepper. Melt the butter in a large skillet or griddle over medium heat. Scoop the potato mixture into the skillet to make 3 inch cakes. Fry until golden and crisp, turning once, about 5 minutes per side.