1/2 cup unsalted butter, 1 cup lightly packed light brown sugar, 1 can sweetened condensed milk, 1/2 cup light corn syrup
Cook over medium heat, stirring constantly, until all ingredients are thoroughly combined and the mixture is warm and starting to bubble. Dip will seem very thin, but will thicken considerably as it cools.
Remove from the heat. Allow to cool slightly before serving warm with fresh apples.
Store leftover dip in an airtight container in the refrigerator for up to a week. To reheat, place in the microwave for about 30-45 seconds, or until warmed through.