Adapted from: http://www.marthamarthablog.com/best-hot-butterbeer-recipe/
10g/ 1 tb. unsalted butter
30g/ 3 tb. powdered erythritol OR xylitol (or 1/4 tsp. stevia, though there may be a bitter aftertaste)
1/8 tsp. butterscotch/toffee/caramel flavoring (or 1/2 tsp. molasses)
1/4 tsp. vanilla extract
1/8 tsp. salt
30g/ 30ml/ 2 tbs. cream
1 tsp. rum (this adds important flavour, but the alcohol content will evaporate once cooked, so add more right before serving if you would like alcoholic butterbeer)
1.5 cups boiling water (or a mixture of hot cream and boiling water)
(more rum, if desired)
Melt all ingredients together except the 1.5 cups of water until bubbling, whisking for 1 minute or until the sweeteners have fully dissolved.
Add the hot water slowly, whisking the whole time, OR pour into a blender with the hot water and blend until frothy and fully combined.
Add more rum if desired, add extra water or cream if too sweet.