01 - Combine warm milk, sugar, and instant yeast in a large mixing bowl. Let stand for 3 to 5 minutes until mixture becomes bubbly and foamy.
02 - Add sourdough discard, melted butter, egg, and salt to the yeast mixture. Stir until thoroughly combined.
03 - Gradually incorporate flour, one cup at a time, mixing until a soft and slightly tacky dough forms. Stop adding flour once the proper consistency is reached.
04 - Turn dough onto a lightly floured surface and knead for 7 to 8 minutes until smooth and elastic.
05 - Place dough in a lightly greased bowl, cover with plastic wrap or a clean towel, and let rise in a warm place until doubled in size, approximately 1 to 1.5 hours.
06 - Punch down risen dough and divide into 8 equal portions. Roll each piece into a smooth log approximately 6 inches long.
07 - Arrange shaped buns on a parchment-lined baking sheet, leaving 2 inches of space between each. Cover and let rise until puffy, 30 to 45 minutes.
08 - Preheat oven to 375°F.
09 - Brush buns with milk and sprinkle with seeds if using. Bake for 18 to 20 minutes until golden brown.
10 - Remove from oven and immediately brush with melted butter for a softer crust. Allow to cool completely before slicing.