01 - Combine warm milk, sugar, and instant yeast in a large mixing bowl. Allow the mixture to sit for 3 to 5 minutes until bubbly and foamy, indicating the yeast is active.
02 - Add sourdough discard, melted butter, egg, and salt to the yeast mixture. Stir thoroughly until all wet ingredients are fully incorporated.
03 - Gradually add flour, one cup at a time, mixing continuously until a soft and tacky dough forms. Stop adding flour once the dough reaches the proper consistency—you may not need the full 4 cups.
04 - Turn the dough onto a lightly floured surface. Knead for 7 to 8 minutes until the dough becomes smooth, elastic, and springs back when pressed.
05 - Place the dough in a lightly greased bowl, cover with plastic wrap or a clean towel, and let rise in a warm area until doubled in size, approximately 1 to 1.5 hours.
06 - Punch down the risen dough and divide into 8 equal portions. Roll each piece into a smooth log approximately 6 inches long, tapering the ends slightly.
07 - Arrange shaped buns on a parchment-lined baking sheet, leaving 2 inches of space between each. Cover and let rise until puffy and expanded, 30 to 45 minutes.
08 - Preheat the oven to 375°F during the final 15 minutes of the second rise to ensure proper baking temperature.
09 - Brush buns with milk and sprinkle with seeds if using. Bake for 18 to 20 minutes until golden brown on top and cooked through.
10 - Remove from oven and immediately brush with melted butter for a softer crust. Allow buns to cool completely on a wire rack before slicing.