Line a baking sheet with parchment paper (or aluminum foil). Set aside.
Chop chocolate into small pieces, then place in a bowl.
Microwave chocolate for 30 seconds, then stir chocolate well. Continue microwaving in 15 second increments, stirring very well in between, until chocolate is melted. (For white chocolate use 10 second intervals. See notes below.)
Spread melted chocolate over parchment paper, about ¼-inch thick, using a spatula.
Sprinkle chocolate with toppings.
Freeze bark until set (about 10 minutes). Then cut into squares with a chef's knife or break into pieces with hands.
Eat bark immediately or store in an airtight container a cool place. Enjoy!
Take your time when melting the chocolate. If it overheats, the chocolate will seize up, and you'll need to start over.White chocolate is more temperamental than milk or dark chocolate, and it takes less time to melt. Start by microwaving it for 30 seconds, then stir really well. Continue microwaving in 10 second (or smaller) increments, stirring very well in between, until chocolate is melted.If you do not have a microwave, use a double boiler to melt the chocolate instead.After the chocolate melts, add additional flavor by stirring in 1 teaspoon of extract (such as almond or peppermint), if you wish.This bark can be topped with almost anything, so don't think you have to stick to nuts! Read the info before this recipe card for tons of creative ideas and tips.You will need about ½ to 1 cup of toppings, depending on their size. For smaller ingredients (like sprinkles), you will only need a few tablespoons. To avoid getting fingerprints on the bark when breaking it into pieces, grasp it with parchment paper (or wax paper) instead of your bare hands.