Best Thermos Flasks UK – Keep Drinks Hot All Day (Tried & Loved by D&L)

On cold, grey mornings, a hot breakfast can feel like the difference between trudging through the day and quietly getting on with it. This easy Thermos porridge with apple & cinnamon recipe is designed for real life: a make-ahead breakfast you can take on the school run, commute or allotment visit – still warm hours later.

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Instead of rushing a bowl at home, you make a slightly looser porridge, pour it into a preheated food flask and let time and insulation do the rest. By the time you’re ready to eat, the oats are soft, the apple is tender and everything tastes like a gentle version of apple pie.

This recipe is written for one generous serving, but it scales up easily if you’re feeding two people with separate flasks.

Why Thermos Porridge Works So Well

A food flask is essentially a tiny, portable slow cooker for oats. Once you’ve poured the hot porridge in and sealed the lid, the residual heat continues to soften the oats without scorching or sticking to a pan.

Benefits of this Thermos porridge apple & cinnamon recipe:

• Hot breakfast you can eat at your desk, in the car (parked!) or after a walk.
• Uses cheap cupboard ingredients – oats, milk, apple, cinnamon.
• Helps nudge you away from buying expensive grab-and-go breakfasts.
• Easy to adapt for dairy-free, higher protein or different fruits.

If you’re building a small “comfort food on the go” routine, this sits nicely alongside our Slow Cooker Comfort Dishes for Chilly Autumn Evenings – dinner bubbling away at home, breakfast sorted for tomorrow.

Choosing the Right Food Flask

For this recipe, you want a wide-mouth food flask rather than a tall, narrow drinks flask. It makes pouring porridge in and eating it out much easier.

Look for:

• Capacity around 350–500 ml per person.
• Wide opening and a lid that doubles as a bowl if possible.
• Stated heat retention time of at least 5–6 hours.

Well-reviewed options include:

• 
  Wide-mouth food flasks for porridge and soup (#ad)
  
• 
  Insulated lunch bags to carry your flask (#ad)
  
• 
  Food flasks and lunch accessories at Tower Housewares (#ad)
  

Once you’ve found one you like, you can use it for leftovers, soups and slow-cooker portions too – part of a very simple “bring your own comfort food” kit for workdays.

Thermos Porridge with Apple & Cinnamon: Ingredients

Serves 1 generously (scale up as needed)

• 40 g porridge oats (about ½ cup)
• 250–275 ml milk or milk + water (dairy or plant-based)
• ½ medium eating apple, cored and chopped into small pieces (no need to peel unless you want to)
• ½–1 tbsp runny honey, maple syrup or soft brown sugar (to taste)
• ½ tsp ground cinnamon
• Pinch of salt

Optional toppings

• Extra chopped apple or a spoonful of apple compote
• Raisins, sultanas or chopped dried apricots
• Chopped nuts or seeds (walnuts, pecans, pumpkin seeds)
• A spoonful of yoghurt when you come to eat it

For easy toppings on the go, small lidded containers are helpful:

Mini snack pots and condiment containers (#ad)

Step-by-Step: How to Make Thermos Porridge with Apple & Cinnamon

1. Preheat the Thermos

1. Boil the kettle.
2. Pour boiling water into your clean food flask, put the lid on and leave it to stand while you cook the porridge.

This helps your Thermos porridge stay hot for longer – you’re not pouring it into a cold container.

2. Cook the Porridge Slightly Looser Than Usual

3. Put the oats, milk (or milk + water), chopped apple, cinnamon and a pinch of salt into a small saucepan.
4. Bring up to a gentle simmer over medium heat, stirring often.
5. Once it thickens, turn the heat down and cook for 3–5 minutes, stirring, until the oats are soft but still a little looser than you’d normally eat at home. They’ll continue to thicken in the flask.
6. Taste and stir in honey, maple syrup or sugar to your liking.

3. Fill the Flask

7. Pour the hot water out of the Thermos.
8. Carefully ladle or pour the porridge into the warm flask, leaving a little space at the top.
9. If using dried fruit or nuts that you’d like to soften, you can stir some in now; keep crunchy toppings back for later.
10. Seal the flask tightly.

Your Thermos porridge with apple & cinnamon will stay hot for several hours. When you’re ready to eat, give it a stir, add any extra toppings and enjoy straight from the flask or into a bowl if you’re at a desk.

Variations on Thermos Porridge

• Apple & raisin: add a small handful of raisins when cooking so they plump up.
• Carrot cake porridge: grate a little carrot in with the apple, add extra cinnamon and a pinch of mixed spice.
• Higher protein: stir in a spoonful of Greek yoghurt or a scoop of your favourite protein powder once it’s in the flask and cooled slightly.
• Dairy-free: use oat, almond or soy milk and sweeten with maple syrup.

Serving & Eating On the Go

A few small habits make this Thermos porridge apple & cinnamon recipe even easier to slot into your week:

• Keep oats, cinnamon and a jar of honey in one easy-to-grab spot.
• Chop apple while the kettle boils or use prepped apple pieces from the fridge.
• Store toppings (nuts, seeds, dried fruit) in small lidded tubs so you can grab them as you leave.
• Keep a spoon or spork tucked into your bag so you’re never without one.

Reusable travel spoon and spork sets (#ad)

If you’re using this as part of a wider money-saving push, pair it with our guide to cutting household bills in the UK without feeling miserable – breakfast from home is one of the easiest daily wins.

Thermos Porridge FAQs

How long will Thermos porridge stay hot?

It depends on your flask, but most decent food flasks will keep porridge warm for 4–6 hours if you preheat them with boiling water first. Check your manufacturer’s guidance and test with water the first time if you’re unsure.

Can I make Thermos porridge the night before?

For best heat, it’s worth cooking the porridge in the morning. If that’s not realistic, you can cook it the night before, chill it in the fridge and reheat thoroughly before pouring into a preheated flask in the morning.

Can I use plant-based milk?

Yes – oat, almond and soy milks all work well in this Thermos porridge with apple & cinnamon recipe. Just choose one you’re happy to drink on its own and keep an eye on sweetness if it’s already sweetened.

Will the apple go brown?

Because the apple is cooked in the porridge, any colour change is mostly hidden in the cinnamon and doesn’t affect taste. If you’re worried, add a squeeze of lemon juice when chopping.

For more small, practical comforts like this – food that fits around ordinary days, not special occasions – join the Danbury & Lovejoy newsletter and explore more ideas from The Kitchen & Larder.