Step 1: Cook the sweet potatoes. Wash sweet potatoes and boil or roast them until very tender. Once cooled, peel and mash until completely smooth. Measure 2 cups of mashed sweet potatoes.
Step 2: Prepare the pie crust. Roll out your pie crust and fit it into a 9-inch pie plate. Crimp the edges. You can blind bake the crust for 10-15 minutes at 375°F (190°C) to prevent a soggy bottom.
Step 3: Cream butter and sugars. In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar with an electric mixer until light and fluffy.
Step 4: Add eggs and vanilla. Beat in the eggs one at a time, ensuring each is fully incorporated. Stir in the vanilla extract.
Step 5: Combine sweet potatoes and milk. Add the mashed sweet potatoes to the mixture and beat on low speed until just combined. Gradually add the evaporated milk, mixing until smooth.
Step 6: Stir in spices. Add the ground cinnamon, ground nutmeg, ground ginger, and optional pinch of salt. Mix until the spices are evenly distributed and the filling is uniform.
Step 7: Bake the pie. Pour the sweet potato filling into the prepared pie crust. Place on a baking sheet and bake in a preheated oven at 350°F (175°C) for 50-60 minutes, or until the edges are set and the center has a slight jiggle. If crust edges brown too fast, cover with foil.
Step 8: Cool completely. Remove the pie from the oven and let it cool on a wire rack at room temperature for at least 3-4 hours, or ideally overnight, for the filling to fully set. Chill in the refrigerator for an hour or two before serving for perfect slices.