Heat the milk in a small pot or microwave until warm to the touch (not hot enough to scald) and dissolve the baking soda in the milk and set aside to cool slightly.
In a medium bowl, combine the flour and cream of tartar. Use a whisk or dough whisk to evenly distribute the cream of tartar through the flour.
In a separate small bowl, crack the egg and add the sugar. Beat with a fork until combined and slightly frothy.
Slowly pour the milk mixture into the egg mixture, stirring with a fork until well blended.
Make a well in the center of the dry ingredients and pour in the wet mixture and use a spatula or dough whisk to combine until the batter is smooth.
Allow the batter to rest for 10 minutes. In the meantime, heat a skillet or frying pan over low heat (an electric frypan makes light work of many pikelets if you are cooking for a crowd).
Grease the hot skillet with a small amount of butter, then wipe away excess.
Test with one small spoonful of batter (the sacrificial pikelet). Adjust the heat if needed—it should form bubbles evenly across the surface before flipping.
Cook 3-4 pikelets at a time, flipping once bubbles appear, and cook until golden on both sides.
Place cooked pikelets on a cooling rack to prevent sweating.
Serve hot or allow to cool completely before adding toppings.