Heat sugar, cream, corn syrup, and butter in a saucepan over medium-high heat, stirring until butter has melted. Clip a candy thermometer to side of pan, and continue to cook until mixture reaches 240 degrees. Remove from heat, and stir in vanilla. Let cool for 5 minutes.Advertisement
Line a baking sheet with parchment paper, and coat with cooking spray. Insert a skewer into stem end of each apple. Dip apples in caramel, and place on sheet. Let stand until set, at least 1 hour. Apples can be stored airtight for up to 1 day.