Boil yams with skin on until a fork or butter knife causes the yams to easily break apart when inserted. Cool yams slightly, then, place in colander and run cold water over them to assist in removing the skins since the yams will be pretty hot.
Beat yams with a mixer on medium, stopping frequently to remove strings from the beaters. Once the strings are removed, add butter and continue to mix.
Add remaining ingredients. You may want to adjust the nutmeg and sugar to your taste. I like my pie sweet with a good amount of nutmeg. Continue mixing the batter until it has a nice smooth consistency. The batter should not be thin or runny and it should not be too thick either. If too thick, add a little more evaporated milk by the tablespoon until batter is smooth.
Pour mixture into pie shell; sprinkle a dash of cinnamon on the top and bake for 50 minutes to 1 hour. TIP: Brush the edges of pie shell with ice water to prevent it from burning before the pie is done.
Brown specs on the top of the pie are an indication the pie is done. Insert a knife in the middle of pie and if it comes out clean, pie is done. Let cool for 1 hour before serving.
This pie is delicious when served with French Vanilla ice cream, a dollop of sweetened whipped cream or cold right out of the refrigerator.