In a bowl or glass container, mix oats, chia seeds and milk. Cover with a lid and place in the fridge before bed. *I prefer my overnight oats in the fridge for at least 8 hours. I used 3/4 cup milk instead of 1/2 cup milk because the chia seeds are thirsty beasts and I prefer my overnight oats a bit moister/creamier.
In the morning, heat up oats in the microwave. I heat mine for 1 min 20 seconds on power level 8.
Mix frozen blueberries into hot oats. This will thaw the blueberries and cool down the oatmeal.
Sprinkle brown sugar on top. You can also use maple syrup if you like.
Add any other toppings you might want like chopped walnuts or other seeds, sliced banana, yogurt, etc.