Chewy Chocolatey Cheerioats Bars

Preheat oven to 350 F.
Spread oats in the bottom of a 9x9-inch rimmed baking pan and toast in the oven until fragrant and lightly browned, about 15 minutes.
While the oats are browning, put the Cheerios, chocolate chips, peanuts, and raisins into a large bowl. Set aside.
Pour the brown rice syrup, brown sugar, and peanut butter into a small, heavy pot and warm over medium heat to dissolve the sugar and melt the ingredients together. Heat until it's a thin, smooth syrup, stirring occasionally. Once the ingredients are melted, stir in the vanilla.
When the oats are done, remove them from oven and add them to the bowl with the Cheerios mixture. Mix well.
Lightly grease the bottom and sides of the pan that you cooked the oats in.
Drizzle the hot syrup over the cereal mixture and use a wooden spoon to quickly work the ingredients together so it is one, uniform lump, with no dry bits left out.
Put it immediately into the greased baking pan and use the spoon to press it down very firmly, filling out the entire pan. Once the mixture has cooled enough to touch, use your hands to press down on the mixture further until it is one solid, uniform block.
Leave it to cool for 30 minutes. Then, invert the bars out of the pan onto a cutting board. Turn it right-side up, and cut it into 25 bars.
Store in an airtight container.
Adapted from a recipe for Banana Nut Energy Bars by the folks at Cheerios.