Combine Kerrygold butter, brown sugar, corn syrup, and condensed milk over medium-high heat.
Stir constantly until mixture boils. Reduce heat to medium and continue stirring until mixture reaches 248 degrees F (measure with a candy thermometer). Remove from heat and stir in vanilla extract.
Insert wooden sticks securely into apples.
Dip apples in caramel mixture and place on parchment paper.
Quickly add desired toppings (the caramel sets fast). Enjoy!