Start by lining your 9x13 inch baking dish with parchment paper. Leave some overhang on the sides to make it easier to lift the bars out later.
In a large saucepan over medium heat, combine the unsalted butter, honey, and light brown sugar. Stir continuously until the mixture is melted and smooth, about 3-5 minutes.
Remove the mixture from the heat and quickly stir in the old-fashioned oats and crispy rice cereal. Mix until everything is evenly coated.
Add the vanilla extract, semi-sweet chocolate chunks, and raisins. Stir well to ensure all the ingredients are fully incorporated.
Transfer the mixture to your prepared baking dish. Press it down firmly into an even layer using a spatula or your hands.
Place the baking dish in the refrigerator for at least 2 hours or until the bars are firm. Once set, remove them using the parchment paper overhang.
Using a sharp knife, cut the bars into your desired size and shape. Store any leftovers in an airtight container at room temperature or in the fridge.