Warm butter (1/2 cup, 113 g) on stovetop until just melted. Stir in sugar (1/4 cup, 55 g, milk (1 cup, 200 g) and active yeast (1 tbsp, 12 g). Cover and allow yeast to proof for 5-10 minutes.
After yeast has proofed whisk in sourdough discard (1/2 cup, 100 g) and 2 eggs.
Pour liquid mixture into bowl of stand mixer and add in flour (4 1/2 cups, 600 g) and salt (1 tbsp, 20 g). Knead on low speed with dough hook until a smooth, elastic dough forms (about 6-8 minutes). The dough should pass the window pane test (see image below).
Form dough into a ball and cover. Place in a warm spot and allow dough to rise until doubled, about 1-1.5 hr.
Once dough is doubled, punch down and place on countertop. Divide dough into 4 equal sections, then divide those 4 sections in 5 individual pieces. For roll size consistency, I recommend weighing out each section. They should weigh about 60-65 grams each.
Roll into balls using tension from the counter top. You should avoid adding extra flour to the dough as not to risk the rolls becoming too dense. Place rolled dough balls into buttered 9×13 baking dish. Cover and allow rolls to double in size, about 30-45 minutes.
Preheat oven to 375°F. Once rolls are doubled in size bake in preheated oven for 25 minutes or until the center rolls internal temperature reach 200°F. If using a glass baking dish, place an aluminum baking sheet on the rack below to prevent the bottoms of the rolls from burning.
Brush hot rolls with butter and allow to cool for 20-30 minutes. Serve warm and enjoy!