In a mixing bowl, combine the cereal, oats and chopped peanuts. If using raisins, add them now. If using either of the chocolate options, wait until later. Set aside.

Grease a 9-inch square baking dish. For easy removal of the bars, I like to also line the pan with parchment paper, allowing the paper to overhang on two of the sides.

In a heavy-bottomed pot that is large enough to hold the cereal mixture, combine the honey, brown sugar and peanut butter. Over medium heat, slowly bring the mixture to a boil, stirring regularly. (It will look foamy when it boils.) When the mixture boils, promptly remove it from the heat, and stir in the vanilla.

Immediately pour the cereal mixture into the hot honey mixture, folding the dry ingredients into the wet ingredients to fully coat. At this point, stir in half of the chocolate pieces. These will get a little gooey from the residual heat. Turn the mixture into the prepared pan, and evenly distribute. A piece of parchment or wax paper makes it easy to press the mixture into an even layer without sticking to a spatula or your hands. Then sprinkle the remaining chocolate pieces and optional coconut over the top, pressing on them lightly to make sure they stick.

Allow the bars to completely cool before cutting. If using parchment paper, lift the bars out of the pan for easier cutting. Store in an airtight container at room temperature for several days–or as long as they last!