These Birthday Cake Brownies are the ultimate birthday bake but in brownie form. Thick and fudgy brownies get a generous layer of funfetti cookie dough running through the middle. Perfect served as they are or warmed up with a little whipped cream.
These are so easy to make, relying on my classic brownie recipe with the addition of funfetti cake mix. Make the cake mix up as described in the recipe. Then, use half this batch for the brownies then you can bake the rest up as cookies!
For these brownies, we rely heavily on the melted butter and light brown sugar to give the fudgy texture and super shiny topping. To make the shiny top on a brownie, there are arguments as to whether it’s the egg, or the molten sugar in the butter, so let’s make sure to do both. This recipe cuts neatly into 9 pieces, but could be sliced smaller, and the recipe is easily doubled. They keep well in the fridge for a few days. That said, they don’t last long if you’ve got lots of happy hungry mouths in the house!

WHEN IT COMES TO MAKING THE BEST BROWNIES, HERE ARE A FEW TIPS TO KEEP IN MIND:
- Quality Ingredients: Always use high-quality ingredients in your brownie recipe. This includes using good quality chocolate, cocoa powder, and fresh eggs. It will make a noticeable difference in the taste and texture of the brownies.
- Don’t Overmix: When combining the ingredients, be gentle and avoid overmixing the batter. Overmixing can lead to a denser and tougher texture. Mix until the ingredients are just combined.
- Proper Pan Size: Use the recommended pan size mentioned in the recipe. Using a smaller or larger pan can affect the baking time and the texture of the brownies. For fudgy and moist brownies, an 8×8-inch square baking pan is usually recommended.
- Do Not Overbake: Keep a close eye on the brownies while they are baking and avoid overbaking them. A slightly underbaked brownie will be fudgy and moist, while an overbaked one can turn out dry. Insert a toothpick into the center – if it comes out with a few moist crumbs, the brownies are done.
- Let Them Cool: Allow the brownies to cool completely in the pan before cutting and serving. This helps them to set and ensures that they hold their shape. It also allows the flavors to develop fully.
- Experiment with Additions: Feel free to get creative with your brownie recipe by adding your favorite mix-ins such as nuts, chocolate chips, or even a dollop of peanut butter. Just make sure not to overload the batter, as it may affect the texture.
Remember, practice makes perfect when it comes to baking brownies. Don’t be afraid to make tweaks and adjustments to the recipe to suit your preferences.

INGREDIENTS REQUIRED
There are no specialist ingredients or equipment required for this bake. I can find everything I need at my local supermarket or grocery store. Also, I use a standard 8 inch square tin for almost all of my traybake recipes for ease. If you do want to convert to 9 inch, you’ll need to play with the quantities a little or they will be too thin. To line a square baking tin, cut two pieces of baking paper that are just narrower than the width of the tin (less than 8 inches wide). Then place one on top of the other in opposite directions, so that all four edges of the tin are covered. This will make removing the bake so much easier!
- Dark/Semi-Sweet Chocolate, Melted
- Unsalted Butter
- Light Brown Soft Sugar
- Granulated Sugar
- Medium Free Range Egg
- Vanilla Extract
- Instant Coffee
- Plain (All Purpose) Flour
- Cocoa Powder
- Funfetti Cake Mix
- Vegetable Oil
TOP TIPS FOR THE BEST Birthday Cake Brownies
- Melted Butter: As mentioned above, this contributes to the shiny top!
- Melted Chocolate: Try to use a higher quality dark chocolate where possible, as this really does contribute to that final flavour.
- Light Brown Sugar and Granulated Sugar: It is the combination of both sugars that creates the fudgy texture and rich flavour.
- Cocoa Powder: Again, where possible try to use a higher quality make. This contributes so much to the flavour and I find some cheap ones really dull the richness!
- Funfetti Cookie Dough: To make the dough, I use my cake mix cookie recipe. Make the full batch but only use half for the brownies. Use the other half to bake as cookies as described in my recipe linked above.
For my Birthday Cake Brownies, I use a basic 8′ square pan (I like this one). I also recommend a good stand mixer or high speed mixer (like this one) to make the brownie mixture. If you want more wild brownie recipe ideas, check out my Pumpkin Spice Latte Brownies. For videos and baking inspiration, head on over to my Instagram. If you make this recipe, don’t forget to drop it a star rating, leave a review or share a photo on your socials!

STORAGE FOR THE BEST Birthday Cake Brownies
Because the brownies have been baked with no unbaked dairy, these can be stored in a cool and dry place. Place in an airtight container before placing in the cupboard or pantry. They will keep for up to 3-5 days this way. A cake tin is a great option if you have one. It can sit out while you serve and eat!
Alternatively, you can freeze the brownie itself. Completely wrap as tight as you can using cling film/Saran wrap. If you have an airtight container too, place it in there before freezing. Let thaw in the fridge before serving!

Birthday Cake Brownies
Ingredients
For the Brownie
- 100 g (½ cups) Semi-Sweet Chocolate Melted
- 170 g (¾ cups) Unsalted Butter Melted
- 100 g (½ cups) Granulated Sugar
- 100 g (½ cups) Light Brown Soft Sugar
- 2 (2) Medium Eggs
- 2 tsp (2 tsp) Vanilla Extract
- 90 g (¾ cups) All Purpose Flour
- 30 g (⅓ cups) Cocoa Powder
For the Birthday Cake Layer
- 15.25 oz Box Funfetti Cake Mix (425g Box in the UK/elsewhere)
- 2 Large Eggs
- 120 ml (½ cups) Vegetable Oil
Instructions
For the Brownie Layer
- Pre-heat the oven to 180℃/360℉. Line an 8×8" square baking pan.
- Melt the dark chocolate by breaking up into small pieces in a bowl and heating for 30 second intervals in a microwave, stirring in between. Set aside to cool whilst making the brownies.
- In a large bowl or the bowl of a stand mixer combine the melted butter, and both the brown and granulated sugars on a medium speed until totally combined. Add the eggs and vanilla and mix again. Add in the melted chocolate.
- Fold in the flour and cocoa powder. Set Aside.
For the Birthday Cake Layer
- Combine the funfetti cake mix, oil and eggs. Stir to form a sticky cookie dough. We will use half of this cookie dough. For the other half: follow my cake mix cookie recipe (place balls of the dough on a sheet pan and bake 15 minutes).
- Pour half the brownie batter into the prepared pan. Top with the cookie dough – you may want to use your hands to spread in an even layer. Top with the remaining brownie batter and spread to cover the cookie dough.
- Bake 25 minutes (add 5 minutes if the batter still looks runny/very wobbly). Remove and let cool before slicing and serving.








