Oatmeal Banana Chocolate Streusel Muffins are bursting with flavors! They are soft and fluffy muffins made with sweet bananas, cocoa, chocolate chips, and oats. Before baking, the muffins have a buttery streusel sprinkled on top that crisps and melts up perfectly.

The combination of chocolate and banana are so good. It's one of my favourites!
These muffins make for the perfect breakfast, snack, or after dinner treat. They are fluffy and hearty!
If you have browning bananas on your counter, you have to try these muffins!
For more muffin recipes, try Chocolate Chip Streusel Muffins, Pecan Banana Muffins, and Double Chocolate Muffins.
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Here is why Oatmeal Banana Streusel Muffins are so good
- Easy to make - All of the ingredients are simple and no electric mixer required!
- Banana and chocolate flavours - Such a good and underrated combo!
- Delicious - These muffins taste so dang good!

Ingredients Notes
Full recipe and ingredients are in the recipe card below. Feel free to scroll through this section to view certain key ingredients we’re using!
All-purpose flour – This flour is used for the muffins and cannot be substituted for any other.
Bananas – 2 large bananas are used. If using frozen bananas, thaw and drain any excess liquid before adding into the bowl.
Brown sugar – I used dark brown sugar, but light brown sugar works as well!
Butter - This will be softened and used for the streusel.
Cornstarch – Used to enhance the texture.
Eggs – Must be at room temperature before starting your bake.
Oil – I used a flavourless oil. You can use any type of oil, but flavoured ones will slightly change the taste.
Oats - Make sure to use rolled oats, also known as large flake oats. Quick oats will not work for this recipe!
Sour Cream – The secret ingredient that makes these muffins so soft and moist! This also stabilizes the muffins and brings out soo much texture.

Step by step instructions
Here is how to make and bake these Oatmeal Banana Chocolate Streusel Muffins. You will need two 12 muffin tins, muffin liners, 3 mixing bowls, a spatula, and a whisk.
Step 1 – Prep. Line 2 muffin liners with 14 liners and set aside. If you need a recommendation, this is my favourite tin. Mash bananas in a large bowl.
Step 2 – Make the streusel. In a medium sized bowl, add all-purpose flour, rolled oats, white sugar, dark brown sugar, cinnamon, and softened butter. Using your hands, mix this until crumbly and combined. Set in the fridge while you make the muffin batter.

Step 3 – Mix together dry ingredients. In a medium-sized bowl, add in flour, cocoa powder, oats, salt, cornstarch, baking powder, and baking soda. Using a spatula, mix until just completely combined.
Step 4 – Whisk wet ingredients. In a large bowl, whisk mashed bananas, oil, eggs, vanilla, sour cream, and brown sugar. Whisk until well combined. There may be lumps from the bananas but that is okay.


Step 5 - Combine dry and wet ingredients. Add the dry into the wet and using a spatula, gently fold until a soft batter forms.


Step 6 - Mix in chocolate chips. Add in the chocolate chips and gently mix until evenly distributed. Don't over-mix!


Step 7 – Scoop. Evenly divide the batter between 14 liners, they should be almost or all the way full. Using a cookie scooper helps big time to minimize the mess. Sprinkle a handful of streusel and chocolate chips on top.


Step 7 – Bake. Bake the muffins at 375°F for 25-30 minutes. The muffins are ready when a toothpick inserted comes out dry with no wet batter.
These muffins stay fresh covered at room temperature for up to 3 days, and in an airtight container in the refrigerator for up to a week!

Expert Baking Tips
Here are a few expert baking tips from my kitchen to yours
- Strain off excess liquid. As bananas thaw, they let out a lot of liquid. This must be strained and removed before using the thawed bananas. If you add the liquid, it will ruin the muffin batter. I recommend draining the excess liquid before mashing and measuring out your bananas.
- Use a gram scale. I cannot emphasize this enough! It is the most accurate way of measuring your ingredients in the kitchen. This is one of my favourites.
- Do not over-mix! A big reason muffins don’t rise or turn out tough is because the batter is over-mixed. Once you see no flour streaks, stop mixing.
- The riper the banana, the better. You want to use bananas that are brown, spotty, and super-ripe. This will give you that sweetness!

FAQ
Can I use frozen bananas?
Yes! But you must strain the liquid out of the bananas. As bananas thaw, they let out a lot of liquid. Make sure there is no extra liquid before mashing and measuring out your bananas.
Do I have to add sour cream?
Yes! This is one of the main ingredients in this recipe. If you are looking for a different banana muffin recipe with yogurt or kefir instead, try My Favourite Banana Muffins.
What do I do with leftover streusel?
Streusel freezes great! Just place any leftovers you may have in a ziplock bag and freeze until needed again. You do not need to thaw it to use it, once you are ready to use it, you can sprinkle it frozen on top of the muffins.
Do I have to add in cocoa powder?
Check out Banana Oatmeal Streusel Muffins.

Check out more muffin recipes
PS : If you enjoyed this recipe, please make sure to leave a STAR REVIEW down below! I'd love to stay connected on Instagram @taffeybakery! To get more recipes follow me on TikTok @taffeybakery!

Oatmeal Chocolate Banana Streusel Muffins
Ingredients
For the muffins
- 1 1/4 cups all-purpose flour
- 1/4 cup unsweetened cocoa powder sifted
- 1 1/2 tsps baking powder
- 1 tsp baking soda
- 1 1/4 cups rolled oats
- 1 tsp cornstarch
- 1/4 tsp salt
- 3/4 cups dark brown sugar or light brown sugar
- 1 tbsp vanilla
- 1/2 cup oil
- 2 eggs room temperature
- 2/3 cups full-fat sour cream room temperature
- 1 1/4 cups bananas 3 medium or 2 large, very ripe
- 3/4 cups semi-sweet chocolate chips
For the streusel
- 1/2 cups all-purpose flour
- 4 tbsp butter softened
- 1/4 cup white sugar
- 2 tbsp dark brown sugar
- 1/4 cup rolled oats
- 1/4 tsp cinnamon
Instructions
For the streusel
- In a medium sized bowl, add all-purpose flour, rolled oats, white sugar, dark brown sugar, cinnamon, and softened butter. Using your hands, mix this until crumbly and combined. Set in the fridge while you make the muffin batter.1/2 cups all-purpose flour, 4 tbsp butter, 1/4 cup white sugar, 2 tbsp dark brown sugar, 1/4 cup rolled oats, 1/4 tsp cinnamon
For the muffins
- Preheat the oven to 375℉. Line 2 muffin liners with 14 liners total and set aside. Mash bananas in a large bowl and set aside.1 1/4 cups bananas
- In a medium-sized bowl, add in flour, cocoa powder, oats, salt, cornstarch, baking powder, and baking soda. Using a spatula, mix until just completely combined.1 1/4 cups all-purpose flour, 1/4 cup unsweetened cocoa powder, 1 1/2 tsps baking powder, 1 tsp baking soda, 1 1/4 cups rolled oats, 1 tsp cornstarch, 1/4 tsp salt
- In a large bowl, whisk mashed bananas, oil, eggs, vanilla, sour cream, and brown sugar. Whisk until well combined. There may be lumps from the bananas but that is okay.3/4 cups dark brown sugar, 1 tbsp vanilla, 1/2 cup oil, 2 eggs, 1 1/4 cups bananas, 2/3 cups full-fat sour cream
- Add the dry into the wet and using a spatula, gently fold until a soft batter forms. Do not over-mix!
- Add in the chocolate chips and mix in a few times. Don't over-mix!3/4 cups semi-sweet chocolate chips
- Evenly divide the batter between 14 liners, they should be almost or all the way full. Using a cookie scooper helps big time to minimize the mess. Sprinkle a handful of streusel and chocolate chips on top.
- Bake the muffins at 375°F for 20-25 minutes. The muffins are ready when a toothpick inserted comes out dry with no wet batter.
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