Basic Overnight Oats Recipe:
1 mashed banana
2/3 cup rolled oats
2 tbsp chia seeds
1 cup liquid (almond milk, rice milk, soy milk, fruit juice, etc.)

Additions:
1 tsp vanilla extract
1 tbsp sweetener (maple syrup, brown sugar, agave, stevia, etc.)
Dried fruit
Nut butters
Fresh fruit
Chopped nuts and seeds