The Interwebs is filled with lots of recipes for homemade butter beer, and this one isn't special--it's just my take on the beverage. The ingredients as measured approximately for one glass are as follows:

-> 1 cup sugar
-> 1/2 cup water
-> 1 Tbs. vanilla extract
-> 2 Tbs. butter
-> 2 Tbs. brown sugar

Optional additions may include a...
-> sprig of mint
-> dash of salt
-> shot of mild alcohol (preferably vodka)

Also, you might want...
-> some quality tea

Step 1: Drown the Ingredients

Combine the sugars, water, vanilla extract and butter (as well as the salt and/or mint, should you so choose) in a small saucepan over medium heat.

Step 2: Tea Time

Make yourself a delicious cup of tea while awaiting the saucepan--a nice Earl Grey or rooibus is recommended.

Step 3: Stir

Stir the mixture over medium heat until it dissolves and begins to roll. Allow it to "boil" for a minute or two or three and then turn the flame to low heat and simmer the mixture until it becomes a viscous syrup.

Step 4: Water (Etc.)

Once a somewhat thick syrup swims in the saucepan, kill the flame and allow the mixture to cool before pouring it into a glass. Add water to taste--about half and half is recommended, though it's quite sweet at this point. To keep to authenticity and add flavour, add a dousing of light alcohol such as vodka (I've not tried rum in it, but it may be just as well). My recommendation is to serve it warm.