These soft and chewy Birthday Cake Blondies are filled with Golden Oreo chunks, melty white chocolate chips, and bright rainbow sprinkles. They're nostalgic, festive, and perfect for any celebration. Best of all, they mix together in one bowl and taste just like your favorite birthday cake!
There is something about the combination of buttery vanilla and rainbow sprinkles that just feels like a celebration. Whether it's an actual birthday, a “half-birthday,” or just a Tuesday that needs a little extra sparkle, these Birthday Cake Blondies are the answer.
If you love the flavor of a classic Funfetti cake but crave the dense, fudgy, and chewy texture of a brownie, you are in for a treat. Unlike a traditional cake that requires multiple bowls and frosting layers, these Funfetti blondies come together in one bowl and don’t require any fancy decorating skills. They are basically “party bars”-portable, shareable, and intensely nostalgic.
For more easy sprinkle treats try Funfetti cupcakes, Sprinkle sugar cookies or Birthday cake cookies.
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Why You'll Love These Birthday Cake Blondies
- One-Bowl Easy: No electric mixer required. You can mix the entire batter by hand in under 10 minutes.
- That “Cake Batter” Flavor: These blondies taste just like birthday cake thanks to clear vanilla extract and plenty of rainbow sprinkles!
- Perfectly Fudgy: These aren’t “cakey”. They are fudgy, gooey in the center, and crispy on the edges.
- Versatile. I love this recipe because you can swap out the sprinkles for different holidays.
Ingredient Notes
- Melted Unsalted Butter: Using melted butter is the secret to a fudgy (rather than cakey) blondie. It creates a dense, rich base.
- Light Brown Sugar & White Sugar: We use a mix of both. The brown sugar provides moisture and chew, while the white sugar helps create those iconic crackly, shiny tops. You can use dark brown sugar as well.
- Clear Vanilla Extract : If you want that exact nostalgic “boxed cake” authentic birthday cake flavor taste, use clear imitation vanilla extract (like Wilton or McCormick). It has a specific marshmallow-like scent that standard regular vanilla doesn’t have. If you don’t have imitation vanilla extract you can use regular vanilla extract as well.
- Egg + Yolk: The extra yolk also creates a chewy texture. Make sure your eggs are at room temperature.
- Golden Oreos: Golden Oreo cookie pieces are added to the batter and works so well with white chocolate.
- White Chocolate : You can use white chocolate chips or chunks.
- Rainbow Sprinkles: Use the long, rod-shaped sprinkles (jimmies) rather than nonpareils (the tiny balls). Nonpareils tend to bleed their color into the batter, turning it gray or streaky.
Substitutions & Variations
- Clear Vanilla: If you do not have clear vanilla, you can also use real vanilla extract. You can even use a combination of vanilla and a little bit of almond extract.
- Frosted Blondies: If you want to go full “Birthday Cake,” let them cool and top with a layer of vanilla buttercream and even more sprinkles.
- Gluten-Free: Use a high-quality 1:1 gluten-free flour blend. Since blondies don’t rely on a high rise, they adapt to gluten-free flour beautifully.
- Dairy-Free: Substitute the butter with melted coconut oil or a vegan butter stick. Make sure to use dairy free white chocolate as well.
Step-by-Step Instructions
Here is how to make these birthday cake blondies. You can use a large mixing bowl with an electric hand mixer or a sturdy whisk. Preheat your oven to 350F/175C. Grease an 8 inch square baking pan and line it with parchment paper, leaving an overhang on two sides.
Mix Fats & Sugars: In a large bowl, whisk together the melted butter , brown sugar, and granulated sugar until smooth.
Mix wet ingredients: Whisk in the egg, egg yolk and imitation vanilla extract until the batter looks slightly pale and well-combined.
Fold in Dry Ingredients: Using a spatula, gently fold in all-purpose flour , baking soda and salt. until just combined and no streaks of flour remain. Do not overmix. The Sprinkles: Gently fold in rainbow sprinkles, Oreo chunks and white chocolate chips .
Bake: Spread the batter into the prepared pan in an even layer. Top with a few extra sprinkles and Oreos. Bake for 20-25 minutes. The edges should be golden brown, but the center should still have a slight jiggle.
Cool: Let them cool completely in the pan for at least 1 hour before slicing. This is crucial for the fudgy texture!
Tips & Tricks
- Don’t Overbake: This is the most important rule. Blondies will look slightly underdone in the center when the timer goes off. They will firm up as they cool. If you wait until they look “dry,” they will be hard once cooled.
- The “Sprinkle Topping”: Reserve a tablespoon of sprinkles to press into the top of the batter right before it goes into the oven. This ensures the top looks vibrant and festive.
- Clean Slices: For those perfect bakery-style squares, let the blondies cool completely in the pan. Lift them out using the parchment paper overhang and use a large, sharp knife to slice in one clean motion.
FAQ's
Most likely there was too much flour added. Use a kitchen scale for accuracy or try the spoon and level method. Spoon the flour into a measuring cup and level with a knife (don't pack it into the measuring cup).
This is a “from scratch” recipe designed to taste like cake mix without actually using it! If you want a cake-mix-based bar, that would be a “cake mix cookie bar,” which has a slightly different, airier texture.
Whisking the eggs and sugars vigorously for about 1-2 minutes until the mixture looks pale helps create that meringue-like thin crust on top.
Yes, Just double the ingredients and bake in a 9×13-inch pan. Adjust the baking time to 30-32 minutes
Storage & Freezing
- Room Temperature: Store these Funfetti birthday blondies in an airtight container for up to 4 days. They actually get even chewier on day two!
- Freezing: Wrap individual squares in plastic wrap and place them in a freezer bag. They freeze perfectly for up to 3 months. Thaw on the counter for 20 minutes for a quick treat.
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Recipe
Birthday Cake Blondies
Equipment
- 8 inch square pan
Ingredients
- ¾ cup (170 grams) unsalted butter
- ¾ cup (155 grams) light brown sugar packed
- ⅓ cup (65 grams) white granulated sugar
- 1 large egg + egg yolk at room temperature
- 1 teaspoon imitation vanilla extract
- 1 ½ cups (180 grams) all-purpose flour
- ¼ teaspoon salt
- ¼ teaspoon baking soda
- ½ cup white chocolate chips
- 7-8 golden Oreos chopped
- ¼ cup rainbow sprinkles
Instructions
- Preheat oven to 350F (175C). Butter, or spray with a nonstick vegetable spray, an 8 x 8 inch (20 x 20 cm) square baking pan.
- In a small saucepan, melt the butter. Remove from heat and set aside to cool.
- In a large bowl beat the melted butter, white sugar and brown sugar until light and frothy (2-3 minutes).
- Add the egg, egg yolk and the imitation vanilla extract and beat until the mixture is well combined.
- Stir in the flour, baking soda and salt until no streaks of flour remain.Do not overmix.
- Gently fold in the chopped Oreos, sprinkles and white chocolate chips.
- Pour the batter into the prepared pan, smooth the top, and bake for about 22 – 25 minutes, or until the top of the bars are dry, golden brown, and a toothpick inserted in the center comes out with a few moist crumbs.
- Remove from oven and place on a wire rack. Cool completely before cutting into squares.
Notes
- Use rainbow jimmies sprinkles, not nonpareils. Jimmies hold their color and won't bleed into the batter.
- Don't overmix the batter once you add the flour. This keeps the blondies soft, chewy, and fudgy in the center.
- For gooier blondies, bake on the lower end of the bake time. The center should look slightly underdone when you pull them out. They will set as they cool.
- Let them cool completely before slicing. This helps the blondies firm up and gives clean, neat squares.
- For clean slices, chill the blondies for 20-30 minutes before cutting.
- If using almond extract, start with ⅛ teaspoon , it's strong and you only need a touch for that funfetti flavor.
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