Yeasted Poppy Seed Apple Buns

Place potatoes in a small saucepan and cover with water. Bring to a boil, then reduce heat and cook, covered, until soft, 10 to 15 minutes. Drain and let cool, 15 to 20 minutes. Pass cooled potatoes through a potato ricer and set aside.

Stir 3/4 cup plus 1 tablespoon milk and yeast together in a small bowl. Let stand until creamy or foamy, about 10 minutes.

Combine potatoes, yeast mixture, flour, sugar, butter, egg, lemon zest, and salt together in the bowl of a stand mixer. Knead on low speed until dough is smooth, elastic, and detaches from the bowl, about 5 minutes; dough should be slightly sticky.

Place dough into an oiled bowl. Turn over to coat. Cover with a damp dish towel and let rise in a warm place until doubled in size, about 2 hours.

In the meantime, mix apple, sugar, lemon juice, and cinnamon for filling together in a bowl. Stir until well combined. Cover and refrigerate filling.

Roll dough out on a lightly floured surface into a 12x14-inch rectangle. Spread filling evenly over dough, leaving about 1/2 inch free on each long side. Sprinkle with poppy seeds. Roll up tightly lengthwise. Brush seams with a little water and pinch to stick together.

Place the roll on a large cutting board, seam-side down. Cut into 1 1/2-inch slices using a very sharp knife.

Fit rolls loosely into a greased 10-inch round or 9x13-inch rectangular baking pan, cut-side down, with a little space between them. Cover with a clean towel and let rise in a warm place until visibly doubled in size, about 45 minutes.

Preheat the oven to 375 degrees F (190 degrees C).

Bake in the preheated oven until golden brown, 35 to 40 minutes.

Meanwhile, stir confectioners' sugar and enough lemon juice together in a bowl to make a thick, spreadable frosting.

Remove buns from the oven. Brush frosting over rolls while they are still warm.