Spread melted butter in 15.5"x10.5"x1 inch baking pan with sides.
Sprinkle dry cake mix over butter.
Top with marshmallows, Cheerios and chocolate chips.
Pour sweetened condensed milk evenly over top.
Bake 25-30 minutes or until golden brown.
While warm, run knife around edge to loosen.
Allow bars to cool 1-2 hours before cutting.
Notes
Even Distribution: When layering the ingredients in the baking pan, ensure an even distribution of marshmallows, Cheerios, and chocolate chips. This ensures that each bite of the bars has a balanced combination of flavors and textures.
Pressing Down: After pouring the sweetened condensed milk over the ingredients, gently press down on the mixture with the back of a spoon or spatula. This helps to compact the layers and ensures that the sweetened condensed milk penetrates into the other ingredients, resulting in gooey and cohesive bars.
Cooling Time: Allow the bars to cool completely in the pan before cutting into squares. This cooling time allows the sweetened condensed milk to set and holds the bars together, preventing them from falling apart when cut. For clean and neat cuts, refrigerate the bars for an additional hour before slicing.