Apples should be refrigerated for at least 30 minutes prior to dipping.
Prepare toppings. In a ziplock bag, place items for crushing like cookies and use a mallet to crush them finely. Smaller candies and bits will stick better than larger ones, so finely chop nuts or candies as necessary. Lay out toppings in small dishes.
Remove the stems from the apples. Stand the apples on a flat surface, stem side up. Insert the lollipop sticks vertically through the center core all the way to the bottom of the apple. Tap the stick with a hammer to push the lollipop stick down if you need to. Alternatively, you can slice the apples into ½ inch thick slices and add the lollipop sticks.
Set out an assembly line with the bowls of candy bars, spoons, and apples on wax paper on a cookie tray for easier transport.
Melt the chocolate. In a microwave, add chopped chocolate to a heat-safe bowl that is large enough to fit the apples in but also not too wide either. Heat for 30 seconds, stir, repeat until smooth.
Work one apple at a time. Tip the container (about 45 degrees) until the chocolate pools to one side. Insert the apple into the chocolate. Swirl and turn the apple to coat with the chocolate until the sides are completely covered as you desire. If necessary, spoon chocolate up the sides to cover more area. Allow to excess to drip off. You can lightly bang the lollipop stick against an empty bowl rim to remove faster.
Dry toppings like nuts, sprinkles, or chocolate chips should be put on right away. I find it best to spoon or press candies on the sides while the apples sit in the dish of candy. You can also lift the apple, turn and set down on each side to press candies on. For toppings like caramel or peanut butter, let the chocolate harden first before topping.
Set apples on wax paper to cool and harden. Repeat chocolate and candy dipping for the remaining apples. Refrigerate until the outer shell is solid.