Peanut Butter-Filled Cereal Squares

In a large bowl, mix together the toasted oat cereal, cornflake cereal, and peanuts.

In a saucepan, combine brown sugar, corn syrup, and butter. Bring the mixture to a boil, then remove it from heat. Stir in the peanut butter and vanilla extract until smooth.

Pour the peanut butter mixture over the cereal mixture. Mix well to coat everything evenly. Press the coated cereal mixture into a 9x13-inch casserole dish.

Refrigerate the dish for at least an hour, or until the mixture is set, before cutting it into squares.