Combine all ingredients except pineapple and pecans in a bowl and stir until well combined. Either portion out mixture into mason jars or another storage container with lids or cover bowl. Place whatever storage container you are using in the fridge overnight or for at least 4-6 hours.
Remove overnight oats from the fridge and stir. Add more milk if needed to reach desired consistency. Top with the crunchy pineapple and Garnish with chopped pecans.
Enjoy or store in the fridge for the future for up to 3 days.