Big Batch Slow Cooked Oven Baked Oatmeal – Meal Prep for the Week

A big batch of oatmeal is a good way to stock-up your fridge with readily available breakfast for the entire week. Not only that it is very easy to cook, there are endless variations that you can make from a simple basic oatmeal recipe. Oatmeal keeps you feel full longer so you can avoid frequent snacking before lunch time arrives.

Slow Cooked Oatmeal in the Oven

Make Ahead Oatmeal – Sweet or Savory

This is a big batch recipe which I do not normally make. I made an exception for this recipe because I eat oatmeal almost everyday of the week. The oatmeal was baked in the oven for 3 hours at low temperature, so you can basically do other things at home will the oatmeal cook. You can also make it on stove top just like how you would cook an oatmeal. You can make it sweet by adding sugar, make it plain by leaving out the sugar, or making it savory by adding savory spices. I opted to make a large batch of sweet oatmeal, one that have brown sugar, raisins and chia seed because this is always what I used as based for most of my oatmeal recipe. This version is very versatile, it woks well with almost any toppings that I love to add. Feel free to substitute the mix-in with your preference.

Brown Sugar and Raisins Oatmeal

Types of Oatmeal

Steel Cut Oats (Irish Oats) – This type of oats has a finer texture but is chewier than traditional oats, they are digested more slowly and it makes you feel full easily. This type is perfect for breakfast cereals as they make you feel full longer.

Rolled Oats (Old Fashioned) – This type of oats are flat, thin and have bigger pieces than Steel Cut Oats. It cooks faster, about 10 minutes for 1/3 cup (depending on how chewy you like it). Although filling, it is not as filling as using Steel Cut Oats, but if your recipe requires minimal cooking time or you do not have much time on hand, this is the perfect type of oats to use. I find that this type is also the one perfect for baking cookies, bars, bread or pancakes.

Quick Oats – This type of oats have flat, light and even thinner pieces as compared to Rolled Oats. This cooks in about 1-2 minutes and are perfect for recipes that calls for a very minimal cooking time. Although it is also a good option for breakfast, it is not as filling as using Steel Cut Oats and Rolled Oats.

Instant Oats – This type of oatmeal has been pre-cooked and dried, because of this, it require no cooking time at all. You just need to add boiling water and let sit for few minutes to soften. This type of oatmeal doesn’t have chewiness and texture and can get mushy at times. This if perfect option when you are traveling and you need something on the go. Simply add hot water and you have an instant breakfast with you.


  • 1 cup Rolled Oats
  • 3 cups HOT Water
  • 3 Cups Milk
  • 1/4 – 1/3 cup Brown Sugar ( Can be substituted with other sweetener but measurement will vary. Adjust as needed)
  • 1/3 cup Raisins – optional
  • 3 tbsp Chia Seed – optional


  1. Pre-heat oven to 300F
  2. Transfer rolled oats in a large oven safe pan (I used a cast iron pan). Pour water and milk then stir.
  3. Bake for 3 hours. Take out of the oven every 1 hour and stir. Add more liquid as needed. At last 1 hour of cooking, add raisins, brown sugar and chia seed. If you want to make it very basic and generic, you can remove raisins and chia seed. You can add 1/2 cup more water if you want it to be lighter. You can use this oatmeal to make different variations everyday. I left 12 variations at the end of the post, some of them could be use this recipe as a base.
  4. Let Cool and transfer in jars. I like using mason jars to portion this. This fits in 3 500ml mason jars.
  5. Serve: Transfer in a bowl the portion that you are going to eat. Microwave for about 1 – 2 minutes then and add topping as desired.
  6. Storage: Keep refrigerated up to 1 week.


One tip when reheating it, add few spoonful of water or milk to thin out the consistency. The oatmeal with or  without chia seed will thicken as it cools, even more when refrigerated. So to bring it back to nice consistency, you need to add a little bit of liquid. For single serving, add 1-2 tbsp of liquid and stir then simply pop it in the microwave for 1 minute. take it out and stir again, adding more liquid as  necessary to achieve the consistency that you like. Easy breezy! Enjoy

12 Oatmeal Variations:

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