In the bowl of a stand mixer, combine yeast, warm milk, and 1 teaspoon sugar. Let sit for 5-7 minutes to allow mixture to bubble and activate.
Whisk in eggs and remaining sugar. Attach dough hook to stand mixer.
In a large bowl, whisk together flour and salt. Add 2 cups of flour mixture to stand mixing bowl. Mix on low speed until dough begins to come together. Add another 1 cup of flour mixture. Mix on low speed until incorporated. Add another cup of flour. Mix until incorporated.
With the mixer running on low speed, add softened butter one tablespoon at a time. Add remaining 1/2 cup of flour and knead until dough is smooth and pulls away from the sides of the bowl.
Transfer dough to a lightly greased bowl. Cover with plastic wrap and let dough rest at room temperature for 75-90 minutes until doubled in volume.