In a medium saucepan, add the brown sugar and water. Heat them over medium-high heat, stirring to dissolve the sugar. Bring the mixture to a boil. Once boiling, reduce the heat to medium and simmer for 4 minutes to reduce it.
Add the butter and stir for about 2 minutes, until it has melted into the brown syrup. Turn off the heat, add the vanilla or maple extract, and stir.
Enjoy warm drizzled over pancakes or waffles.
Storage & future use:
Allow the brown sugar syrup to cool down. Then, transfer it into a jar or old syrup bottle. Refrigerate for up to a month.
To reheat, microwave in 15-second intervals if the jar or bottle is microwave-safe, or heat the amount you need in a smaller dish or measuring cup. You can also warm it up in a small saucepan over low heat, stirring until the syrup is heated through.
Notes
Both light and dark brown sugar work to make this recipe. The difference between the two is the amount (%) of molasses; the darker one has more and yields a richer/deeper syrup flavor.