Transfer the yeast mixture to the bowl of a stand mixer fitted with the paddle attachment. Add the shortening, egg, sugar, salt, and 1 ½ cups of the flour and beat on low speed until combined, about 2 minutes. Add the remaining 1 ½ cups flour, raise the speed to medium, and beat until incorporated, about 30 seconds. Switch to the dough hook and beat on medium speed until the dough is smooth and pulls away from the bowl, 3-4 minutes. Transfer to a well-oiled bowl, cover with plastic wrap or a kitchen towel, and let the dough rise in a warm spot until doubled in size, about 1 hour.