Summarize:

Fill a saucepan with 1 to 2 inches (2.54 to 5.08 centimeters) of water, and place a heat-safe bowl on top. Make sure that the bottom of the bowl does not touch the surface of the water. Turn the heat on to low, and bring the water to a simmer. Add the chocolate and wait for it to melt. This will take about 4 minutes. Do not stir the chocolate as it melts. Let the butter and syrup sit in the chocolate for about a minute or two before folding it in with a rubber spatula. Keep folding with your rubber spatula until everything is evenly combined. You can use plain rice crispy cereal for this, or cocoa-flavored rice crispy cereal. The best size to work with is something around 9 by 13 inches (22.86 by 33.02 centimeters) although a 9-inch (22.86 centimeters) square-shaped pan will also work. If you are in a hurry, you can chill them in the freezer for about 20 minutes, or until they turn firm. Cut them in the pan first, then scoop them out using a spatula. If you try to remove the entire rice crispy out of the pan, it may break. You have enough to make 16 to 24 servings.
Assemble a double boiler. Melt the chocolate over low heat in the double boiler. Add the butter and syrup into the chocolate. Remove the bowl from the saucepan, then fold in the rice crispy cereal. Pour the mixture into a greased baking pan. Chill the rice crispy treats in the fridge for 1 to 2 hours. Cut the rice crispy treats into squares, then serve them.