Pour the yeast mixture into the bowl of a stand mixer fitted with a dough hook. Add the softened butter, egg, salt, and two cups of flour. Mix until the batter is smooth.
With the mixer running, slowly add the rest of the flour until the dough forms a soft ball. Increase the mixer speed to high so that the dough hook can knead the dough.
After about two to three minutes, the dough should be tacky but not sticky. If it’s sticky, add a small amount of flour in batches until the dough is no longer sticky.
Place the dough in a greased bowl and turn to coat it. Cover the bowl with a dish towel and leave it in a warm spot to rise until it’s doubled its size. This usually takes about 45 to 60 minutes.
Cut the dough into approximately 24 to 30 squares. Place them on the prepared baking sheets, cover them with a dishtowel, and leave them to rise for 45 to 60 minutes or until doubled in size.