Using an electric mixer or stand mixer fitted with a dough hook, beat the egg, butter, sugar and salt in to the yeast mixture. Add half of the flour (2 cups plus 2 tbsp), and mix until combined, then mix the rest of the flour until the dough pulls away from the sides of the bowl. Add more flour if the dough is too wet. Transfer it to a floured surface, and gently knead it until smooth. Grease a large bowl with a little oil transfer the dough to the bowl and cover.