Baked Oatmeal Marshmallow Bars (Vegan)

Sweet and gooey oatmeal marshmallow bars – the perfect treat! Easy to make and ready in just 30 minutes or less.

I’m all about jazzing up some delicious sweets and these Oatmeal Marshmallow Bars are exactly that: an exciting snack! The vegan marshmallows add wonderfully to a crunchy texture of the baked oatmeal and they bring in a delicious gooey-ness into this tasty vegan treat. They are easily baked on an oven tray or rectangular cake tin and cut into portion sizes, and they can also be kept in the fridge or freezer if you decide to enjoy them another time! The perfect delicious treats for bonfire night – but also any day of the year, if you ask me. 

What you’ll need to make oatmeal marshmallow bars



  • mixing bowl
  • spatula
  • 20 cm x 20 cm rectangular cake tin (8-inch x 8-inch) 

How to make these oatmeal marshmallow bars

To create these tasty oatmeal snacks, there are a few simple steps involved, so get your ingredients ready and let’s dive right in! 


It’s all in the preparation! So let’s start by lining a rectangular or square cake tin first (you can also go for round, they’re just as tasty!) – it should be roughly 20 cm x 20 cm big (that’s 8 x 8 inches!) to give them the right density and height. If you’re using a different size and spreading out your ingredients thinner, make sure to adjust your oven temperature and baking time! I can only recommend having a close eye on them during baking to figure out the best combo for your cake tin & oven.

Preheat your oven to 190°C (374°F.

Oatmeal batter

Now, let’s get into creating our oatmeal batter for these vegan marshmallow bars! In a mixing bowl, combine the coconut oil and the soft brown sugar. Use an electric whisk to cream the coconut oil and sugar mixture. It should usually take 4-5 minutes until creamy. 

Next, mix in the oats, oat flour, salt and baking soda and then mix until everything becomes a sort of crumbly texture – similar to a typical crumble!


Use about 2/3 of this crumbly oat mixture to place it onto the bottom of your lined cake tin. Firmly and evenly press it into the bottom to create an even layer of the oat mixture. You can use the bottom of a glass to even out the surface. 

Afterwards, place the chocolate chips and marshmallows on top – no need to be super neat with this, but I recommend spreading them somewhat evenly across the oatmeal layer. If your marshmallows are pretty big (like in my case!) you can either add them whole or tear them apart if you like your bars to be even on top – that’s exactly what I did on this occasion. 

Sprinkle the rest of the oat mixture on top, creating a wonderful crumb for the top of the bars. 


Transfer your cake tin into the fully preheated oven and bake at 190°C (374°F) for 15-20 minutes or until the bars are becoming golden on top. They will slightly expand during the baking process due to the marshmallows. 

Once done, remove from the oven and allow for the bars to cool down completely before cutting – during that time the bars and marshmallows will harden slightly, holding the oatmeal marshmallows bars together – you can of course totally embrace the mess and eat them hot (very tasty actually, ha!) 

This recipe is:

  • 100% vegan
  • easily made gluten-free
  • deliciously sweet
  • quick and easy to make
  • oven-baked
  • using vegan marshmallows
  • a tasty treat!
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Baked Oatmeal Marshmallow Bars (Vegan)

  • Author: romylondonuk
  • Prep Time: 15
  • Cook Time: 15
  • Total Time: 30 minutes
  • Yield: 9 1x
  • Category: Treats
  • Method: Baked
  • Cuisine: American
  • Diet: Vegan


Sweet and gooey oatmeal marshmallow bars – the perfect treat! Easy to make and ready in just 30 minutes or less.


  • 180ml dairy-free spread, soft
  • 200g soft brown sugar
  • 170g oats
  • 200g oat flour
  • 1/2 tsp fine salt
  • 1/s tsp baking soda
  • 200g vegan marshmallows (I used Dandies)
  • 180 g dairy-free chocolate


  1. To create your marshmallow squares, first, start by combining the coconut oil and the soft brown sugar with an electric whisk until creamy. Mix in the oats, oat flour, fine salt, and baking soda and continue to mix until you get a crumbly texture.
  2. Line a 20 cm x 20 cm (8-inch x 8-inch) rectangular cake tin, and crumble about two-thirds of the crumble mixture onto the bottom. Place baking parchment on top and use the bottom of a tall glass to even out the surface.
  3. Next place your chocolate chips and marshmallows on top. The whole marshmallows or simply tear them apart into two halves and put them on top.
  4. Sprinkle with the remaining crumble mixture and place into the preheated oven at 190°C (374°F) for 15-20 minutes.
  5. Let the squares cool down entirely before cutting & enjoy!

Keywords: vegan oatmeal bars, oatmeal marshmallow bars, vegan dessert, dessert with marshmallows

If you love marshmallow treats, why not try these other ones from the blog:


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