Melt 1 stick of butter in 15 x 10 x 1 inch cake pan. Sprinkle 1 box German chocolate cake mix over it and pat down. Sprinkle on in layer, 1 1/2 cups mini marshmallows, 1 cup chopped pecans, 6 ounces of chocolate chips, and 2 cup Cheerios. Drizzle 1 large can sweet condensed milk over top. Bake at 375 degrees for 20-25 minutes or until brown.