Harry Potter Butterbeer (and Cream Soda)

Ingredients:

• 1 cup light or dark brown sugar
• 2 tablespoons water
• 6 tablespoon butter
• 1/2 teaspoon salt
• 1/2 teaspoon cider vinegar
• 3/4 cup heavy cream, divided
• 1/2 teaspoon rum extract
• Four 12-ounce bottles cream soda

Directions:

1. In a small saucepan over medium, combine the brown sugar and water. Bring to a gentle boil and cook, stirring often, until the mixture reads 240 F on a candy thermometer.
2. Stir in the butter, salt, vinegar and 1/4 heavy cream. Set aside to cool to room temperature.
3. Once the mixture has cooled, stir in the rum extract.
4. In a medium bowl, combine 2 tablespoons of the brown sugar mixture and the remaining 1/2 cup of heavy cream. Use an electric mixer to beat until just thickened, but not completely whipped, about 2 to 3 minutes.
5. To serve, divide the brown sugar mixture between 4 tall glasses (about 1/4 cup for each glass). Add 1/4 cup of cream soda to each glass, then stir to combine. Fill each glass nearly to the top with additional cream soda, then spoon the whipped topping over each.

From: (#1 of) http://wizardingworldpark.com/butterbeer-recipes/

Cream Soda:
2 cups sugar 
1 cup water 
1 tablespoon vanilla extract 
a healthy supply of seltzer (carbonated water), half and half, and cubed or crushed ice