In a heavy duty saucepan, combine granulated sugar, seeds scraped from vanilla bean, and water
Cook over medium-high heat, whisking constantly until sugar is dissolved
Continue to cook for a few minutes until caramel reaches a deep amber (do not stir)
Remove from heat and immediately whisk in heavy cream
Stir in milk and sea salt
Drizzle liberally over apple cake or refrigerate until ready to serve
Notes
Make ahead tip: Caramel sauce can be made up to one week ahead of time. Just heat it gently over the stove or in microwave just prior to pouring over cake and serving
Recipe by Keep It Sweet Desserts at http://www.keepitsweetdesserts.com/vanilla-bean-apple-bundt-cake/