Overnight oats, just steel cut oats in whole milk left in the fridge for at least 4 hours. Healthier and cheaper than a box cereal and so so easy. But if I didn't think ahead to chuck some in the fridge beforehand, then it's gotta be hardboiled eggs. I always have eggs in the fridge and chucking them in a pot and waiting 11 minutes is as easy as it gets.

Well, aside from eating fruit/berries with cheese and crackers but that could be argued to be a snack not a meal.