Place the sugar and orange zest in the bowl of a stand mixer and run the mixer for 30-45 seconds or massage togetherwith your finger tips.
Add the flour, yeast, salt, milk and eggs.
Using the paddle attachment, beat for 2 minutes on medium until combined.
With the mixer running, add the butter a tablespoon at a time and mix until all the butter is incorporated.
Switch to the dough hook attachment and beat at medium speed for 10-12 minutes.
The dough is ready when it has come away from the sides of the bowl and formed a ball around the hook. It will also look very smooth and you will be able to stretch the dough very thin without it breaking. (Window Pane Test)
Place the dough in a greased bowl, cover with plastic wrap and let it proof until doubled in volume, on the counter (1- 1 ½ hours) or place in the refrigerator to proof overnight.