While the pie crust dough is first cooling in the refrigerator, or whenever your Thanksgiving Gantt chart
says so, work on the pie's filling.
You need to soften the sweet potatoes to more easily mix their flesh in with the rest of the filling.
Stab the sweet potatoes with a fork, and microwave them for 5 - 10 minutes -- depending on the strength of your microwave -- or until soft but not mushy. Cut them in half and scoop out the flesh. I held my still-hot potatoes with a pot-holder while scooping. Mix in the butter and lightly mash, but don't puree.