You are not five, this is your parents reverting back to their learned way of dealing with their child that they never let go of or grew out of doing. Also, sadly your parents are probably older being that you are 50 and often what can happen when parents get older is they tend to express their "faults/flaws" more as they can begin to lose their filter. Your father sounds like a bossy crotchety old man.

Now, stand up to them and be assertive and don't allow yourself to act like a child again. Next time eat your cake and then when you are done "walk" up the stairs and say good night.