Place 1/4 cube of butter
in a microwave-safe bowl and melt it. Pour Root Beer
soda into a tall microwave-safe glass and heat on 50%
for 30 seconds or as needed so it is moderately warm.
Warning: If it is warmed too much, it won't
be fizzy or taste good. Pour 1 teaspoon of melted
butter into the Root Beer a little at a time, stirring
constantly. After butter and Root Beer is well blended,
gently add a little bit of cream and stir. It may take
a few times to determine the amount of butter and cream
needed to make the perfect-tasting ButterBeer!