Combine crackers with cereal in a large mixing bowl; set aside.
Cook corn syrup and brown sugar in a saucepan over medium heat 4 to 5 minutes, stirring occasionally, until mixture comes to a boil just around edges. Remove from heat; stir in butter, baking soda and vanilla. (OR in a 1-quart microwave-safe bowl, microwave on HIGH (100%) for about 2 minutes or until syrup boils.)
Pour syrup over cereal mixture and stir to coat completely. Transfer to a greased 13 x 9-inch pan; press firmly to level. Place chocolate bars in a single layer over cereal mixture; sprinkle with marshmallows.
Bake in a preheated 400°F oven for 5 to 8 minutes or until marshmallows are puffed and lightly browned. Remove from oven and top with mini chocolate chips.
Refrigerate for 1 hour until firm; cut into squares. Store in tightly closed container for up to 2 days.