Heat the oven to 400°F. Scrub the sweet potatoes, prick each a few times with a fork, and bake directly on the rack with a sheet pan underneath for 50 to 70 minutes, until a knife slides in with no resistance and syrup bubbles from the ends.

Cool until you can handle them, then slip off the skins. Mash the warm flesh well and measure out 3 cups.

Beat the softened butter, granulated sugar, and brown sugar into the warm mash until completely smooth. If the mash is stringy, push it through a fine mesh sieve at this stage.

Let the mixture cool to barely warm, about 10 minutes. Beat in the eggs one at a time until fully absorbed.

Add the cinnamon, nutmeg, ginger, cloves, salt, and vanilla. Pour in the evaporated milk in a slow stream while beating, until the filling is smooth and pourable.

Reduce the oven to 350°F. Pour the filling into the unbaked pie crust, close to the rim.

Bake 50 to 60 minutes, until the edges are set and slightly puffed and a silver dollar sized circle in the center still wobbles when the pan is nudged. Shield the crust rim with foil at 30 minutes if it browns too fast.

Cool on a rack at least 4 hours, preferably overnight, before slicing. Serve with whipped cream.