Place two jars on the counter and fill each with ½ cup oats, ½ of the mashed banana, 2 teaspoons of peanut butter, ¾ cup of milk, and ¼ teaspoon vanilla. With a spoon, stir to combine well and cover with a lid.
Refrigerate for 8 hours or overnight.
In the morning, stir to combine, top with your favorite toppings. Enjoy cold or warmed in the microwave for 30 seconds to 1 minute.