In a saucepan over medium-high heat, bring apple cider to a boil. Add vanilla bean seeds scraped from pod and drop in the pod itself. {You'll pull this out later.} Continue to boil until reduced by about half, about 12-15 minutes.

Add brown sugar and butter and stir until melted in and well incorporated. Reduce heat to medium.

Allow the mixture to continue to boil until the bubbling starts to slow down as the liquid becomes more thick and syrupy, about 7-10 more minutes. {You'll have to keep an eye on it to make sure it doesn't burn.} I didn't use a candy thermometer for this, but you'll want the mixture to be pourable but thickened -- it will thicken some more after it cools.

Carefully pour hot sauce into a heatproof container or jar and allow to cool before sealing and decorating.

Pour over everything. :)