In a container (can be any shape), crush Weetabix biscuits. Add milk and flatten the Weetabix base with a back of a smooth.
Add mashed or sliced bananas on top.
In another bowl, combine yogurt, peanut butter, and cinnamon. You can also add your sweetener of choice, if desired. Spread on top of the Weetabix and banana layer.
Close the container lid and store in the refrigerator overnight. Top with more banana, coconut, granola, or any toppings of choice right before enjoying.
Notes
There's no need to take extra care to crush the Weetabix thoroughly. It will soften once combined with milk.
I recommend using plain yogurt instead of flavored yogurt, especially for babies and toddlers, so you can control the amount of sugar.
Have fun experimenting with all kinds of toppings - see above for suggestions.