Line a baking sheet with aluminum foil and butter the foil generously. Wash and dry the apples and insert a wooden stick into the stem end of each apple, then set aside.
Combine the sugar, butter, condensed milk, corn syrup and salt in a large, heavy, unlined metal saucepan. Place the pan over medium-low heat, and stir constantly with a wooden spoon until the sugar dissolves, about 15 minutes. Brush down the sides of the pan occasionally with a wet pastry brush to prevent crystals from forming. Increase the heat to medium-high and continue cooking, brushing the sides with a pastry brush (but not stirring), until a candy thermometer registers 236ºF, about 10 minutes.
Pour the caramel into a deep metal bowl, and allow to cool until a candy thermometer registers 200ºF, about 15 - 20 minutes. Do not scrape the sides of the pan when pouring the caramel into the bowl, and do not stir the caramel while it is cooling.
In a small saucepan bring the cream just to a boil. Put the chocolate in a metal bowl and pour the hot cream over it, stirring constantly until smooth. Pour the desired apple decorations into bowls.
Holding the wooden stick, dip an apple all the way into the cooled caramel. Lift the apple out and hold for 30 seconds to let the excess caramel drip back into the bowl, then place on the greased baking sheet. Repeat with the remaining apples and caramel, leaving a 2 – 3-inch space between the apples on the sheet. (Note: If the caramel becomes too thick for dipping, whisk 2 tablespoons heavy cream into the caramel and quickly warm the bowl over low heat.)
Dip the apples one-by-one into the melted chocolate, allowing the excess to drip into the bowl, then roll the apples into the desired optional toppings. Chill the apples until the decorations are set, about 1 hour. Cover with plastic wrap and refrigerate until ready to eat.
Yield: 10 - 12