Wash and dry the apples thoroughly and then remove the stems by twisting until they pop off.
Insert a wooden stick into each apple where the stem was removed. Set aside.
In a heavy-bottomed large saucepan, combine the butter, brown sugar, sweetened condensed milk and corn syrup over medium low heat until everything is melted and combined.
Increase the heat to medium high and bring to a rolling boil while stirring constantly.
Stir constantly until when the temperature reaches 240° F and immediately remove from the heat.
Add the large marshmallows to the caramel mixture and slowly stir and fold until completely combined.
Dip each apple into the caramel, tipping the sauce pan partially on its side while slowly twisting the apple to coat the entire apple with caramel.
Shake and twirl the apple over the sauce pan to remove any excess caramel.
Scrape the bottom of the apple on the side of the pan before placing on a silicone lined cookie sheet.
Repeat with the remaining apples.
Top your apples! Some toppings (like pretzels or toasted coconut) stick better if you roll a still warm and not set caramel apple into the topping. Other toppings, like chocolate drizzle, or a full chocolate coating stick better when you wait until the caramel apple is completely set before adding the toppings.
Store at room temperature for up to 2 days or in the fridge for up to 4 days.
Cut with a large knife and enjoy!