In a measuring cup or small bowl, whisk the warm milk and 1 teaspoon of the sugar until dissolved, then sprinkle the yeast evenly over the top. Let stand for 5-10 minutes, until the yeast looks foamy and smells yeasty.
In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, combine the softened butter, remaining sugar, and salt. Beat on medium speed until smooth and slightly creamy, 1-2 minutes, scraping down the bowl once or twice.
Add the eggs one at a time, mixing on low after each addition until incorporated. Add the foamy yeast mixture and mix on low just until combined.
With the mixer on low speed, add 3 1/2 cups of the flour, about 1 cup at a time, mixing just until a soft dough forms and most of the flour is absorbed. Switch to the dough hook attachment.
Continue adding the remaining flour, a few tablespoons at a time, kneading on low speed until the dough is smooth, elastic, and slightly tacky but not sticky, 5-7 minutes. You may not need all of the flour. Stop adding it as soon as the dough cleans the sides of the bowl but still feels soft.
Lightly coat the inside of a clean bowl with neutral oil or cooking spray. Shape the dough into a ball, place it in the bowl, and turn it once or twice to coat. Cover tightly with plastic wrap or a clean kitchen towel and let rise in a warm, draft-free place until doubled in size, 1 to 1 1/2 hours. The dough is ready when an indentation made with your fingertip springs back slowly but not all the way.