Rice Krispie bars.
The "original" ones. NO peanut butter, no chocolate. Just Rice Krispies, butter, and marshmallows.
Unfrosted brownies - maybe a powdered sugar dusting on them.
Oatmeal raisin cookies.
Make the cookies small and cut the bars small. People can always go back for seconds, but sometimes one just wants a bite or two of a sweet.