Spray a medium bowl with cooking spray. Set aside.
In the bowl of an electric mixer fitted with the dough hook, combine flour, sugar, yeast, salt, soda, butter, and buttermilk.
Mix on low speed 1 minute, until well combined.
Increase speed to medium.
Knead for 8 minutes, until dough is smooth and elastic.
Turn into prepared bowl.
Let rise at warm room temperature (78℉) until doubled in bulk, about 2-2 1/2 hours. (If not using a proofing box with a water tray, cover dough with plastic wrap.)