Prepare the sweet potatoes Peel and cut sweet potatoes into chunks, then boil or roast until fork tender. Mash until very smooth with no lumps remaining. About 2 medium large potatoes will yield the needed 2 cups mashed.

Mix the sugar and butter In a large bowl, beat together granulated sugar and softened butter until well mixed. The mixture should look even and a little fluffy.

Blend in the sweet potatoes Add mashed sweet potato and blend well. Look for a smooth, uniform orange batter. Bits of potato should be well blended at this stage for an even texture.

Add eggs and vanilla Beat in the eggs, one at a time, then pour in the vanilla extract. Keep mixing until glossy and loose.

Add evaporated milk and seasonings Pour in evaporated milk, then sprinkle in cinnamon, nutmeg, and salt. Stir until completely mixed, scraping down the sides of the bowl so all spices blend evenly.

Pour the filling into the pie shell Pour the filling into the prepared pie crust. The surface should be smooth and even. Gently tap the pie plate to pop bubbles and level the batter.

Bake Place the pie on the center rack of an oven preheated to 350°F (175°C). Bake for 50 to 60 minutes. The finished pie should look mostly set with a slightly puffed center that jiggles gently, like gelatin, when nudged.

Cool properly Remove and cool the pie completely on a rack. The aroma should be nutty and buttery, with rich orange color. Letting the pie cool to room temperature allows it to finish setting and keeps slices neat when cut.