01 - Combine warm milk, sugar, and yeast in a large mixing bowl. Let sit for 3–5 minutes until mixture becomes bubbly and foamy.
02 - Add sourdough discard, melted butter, egg, and salt to the yeast mixture. Stir until fully incorporated.
03 - Gradually add flour, 1 cup at a time, mixing after each addition. Continue until a soft, tacky dough forms. You may not need all 4 cups—stop when dough holds together but still feels slightly sticky.
04 - Turn dough onto a lightly floured surface. Knead for 7–8 minutes, pushing dough away with heel of hand and folding back toward you, until smooth and elastic.
05 - Place dough in a lightly greased bowl, turning once to coat. Cover with plastic wrap or warm towel. Let rise in a warm, draft-free area until doubled in size, approximately 1 to 1.5 hours.
06 - Punch down risen dough to release air. Divide into 8 equal portions. Roll each piece into a smooth log about 6 inches long, tapering ends slightly.
07 - Arrange shaped logs on a parchment-lined baking sheet, spacing 2 inches apart. Cover loosely and let rise until puffy and expanded, 30–45 minutes.
08 - Preheat oven to 375°F during final rise.
09 - Brush buns with milk and sprinkle with seeds if using. Bake for 18–20 minutes until deep golden brown on top and sounds hollow when tapped.
10 - Remove from oven and immediately brush with melted butter for softer crust. Transfer to wire rack and cool completely before slicing.