Combine sweetened condensed milk, eggs, vanilla and lemon extract, and sweet potato puree in mixing bowl. Whip to aerate and set aside. Combine dry ingredientsand fold wet into dry gently let set for ten minutes. Do not overmix, (it will make them tough).(ATTENTION THE NUTMEG AND CINNAMON GO INTO THE MUFFIN MIX AND NOT THE ICING, SORRY FOR THE TYPO FOLKS)!!!!!