3cupsboiling water (approximately)more or less, to taste*
Instructions
Using an electric mixer, beat butter, brown sugar, syrup, spices, vanilla, and salt until combined.
Place the butter in the bottom of a pitcher or large glass measuring cup. Add the rum, followed by the boiling water (start with 2 cups of water, taste, and add more until you get it right where you want it. I used right around 3 cups total) . Whisk until combined. Serve immediately. Garnish with whipped cream, if desired.
Notes
*Adjust the amount of rum or water to make the drink stronger or weaker. Use this recipe as a guide, adapting to suit your taste preferences. See the post (above) for ideas for switching up the flavorings.