Name: Easy Homemade Birthday Cake Blondies (45 minutes)
Prep time: 15 min
Cook time: 28 min
Total time: 43 min
Yield: 16
Ingredients: 175 g (1 1/4 cups) all-purpose flour; 1 teaspoon baking powder; 1/2 teaspoon salt; 113 g (1/2 cup) unsalted butter, melted; 165 g (3/4 cup) light brown sugar; 55 g (1/4 cup) granulated sugar; 1 large egg, at room temperature; 1 large egg yolk, at room temperature; 2 teaspoons pure vanilla extract; 150 g (3/4 cup) white chocolate chips; 40 g (1/4 cup) sprinkles; 4-5 Gold Oreo Cookies, roughly chopped or broken

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Celebrate every day with these ultra-soft Birthday Cake Blondies packed with rainbow sprinkles, Golden Oreos, and white chocolate chips for the ultimate birthday cake flavor without the need for an actual cake!

Overhead shot of birthday cake blondes cut into squares with sprinkles around.

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Listen up, baking besties! Today we're throwing a party with these ridiculously good birthday cake blondies. I've tested this recipe multiple times because I needed it to hit that perfect balance of soft and chewy while absolutely LOADED with all the classic birthday cake vibes!

These blondies are what happens when you can't decide between cake and cookies–you get the best of both worlds! They're buttery and dense with a vanilla-forward flavor that screams birthday cake, even without any actual cake mix. The texture is what dreams are made of: slightly crisp edges giving way to chewy centers.

I've packed these with rainbow sprinkles, chunks of Golden Oreos for that familiar birthday cake cookie flavor, and white chocolate in every bite. If you've tried my birthday cake brownies, birthday cake cupcakes, or these stuffed birthday cake cookies, you already know I don't mess around when it comes to celebration-worthy treats!

What are Blondies?

Blondies are like the vanilla-loving cousin of brownies–rich, chewy, and totally indulgent, but with a warm, buttery vanilla flavor instead of chocolate. While they might look similar to cookie bars, blondies are their own delicious category. Unlike cookie bars, which tend to have a firmer, cookie-like texture, blondies have that signature fudgy consistency we all love in brownies (with the help of light brown sugar). Think gooey, soft crumb, and just a little bit dense in the best way possible.

Ingredient Notes

Butter - We’re using melted butter for the perfect chewy texture. I always use unsalted butter to control the amount of salt in my recipes. If you have salted butter, reduce the salt to ¼ teaspoon.
Eggs - Room temperature eggs are non-negotiable! Set them out for at least 30 minutes before baking, or if you're impatient like me, just put them in warm water for 10 minutes and you're good to go!
Vanilla - Don't skimp on the vanilla! This is where so much of our birthday cake flavor comes from. Use PURE vanilla extract. For a bonus flavor, you can substitute ½ teaspoon of the vanilla with almond extract.
White chocolate - We’re using white chocolate chips for this recipe. You can substitute them with chopped white chocolate for melted pools of chocolate.
Sprinkles - For these blondies, we want sprinkles (jimmies) NOT nonpareils (the tiny balls), which can bleed color throughout your batter. I use rainbow sprinkles because they hold their shape and give a fun pop of color.
Golden Oreos. Any vanilla cookie sandwich can be used in place of the golden Oreos. If you prefer, use traditional Oreos or chocolate cookie sandwiches!

Please see the recipe card below for the full list of ingredients and measurements!

What Pan Sizes Can You Use?

This recipe is for an 8x8-inch pan, which gives you thick, chewy birthday blondies with that perfect gooey center. But don’t worry if you don’t have one! You can use a 9x9-inch pan instead–just know the blondies will be a bit thinner, so keep an eye on the bake time as they may cook slightly faster.

If you’re feeding a crow (or just want more blondies, because why not?), double the recipe and bake it in a 9x13-inch pan. You’ll get a bigger batch of equally delicious, slightly thinner blondies perfect for sharing as a blondie cake.

Step-By-Step Instructions

Whisked flour, baking powder and salt in a mixing bowl.

Combine dry ingredients. Give the flour, baking powder, and salt a good whisk.

Whisked melted butter and granulated sugar in a mixing bowl.

Combine butter and sugar. In a separate bowl, whisk together until smooth.

Whisked melted butter, eggs, and granulated sugar in a mixing bowl.

Combine wet ingredients. Add the eggs and vanilla to the butter and sugar mixture and whisk vigorously for 1 minute.

Birthday cake blondie batter in a mixing bowl.

Add dry ingredients. You want to gently fold the dry ingredients into the wet ingredients until mostly combined. It’s okay to see a few streaks of flour.

Mixing bowl of birthday cake blondie batter with sprinkles and white chocolate chips on top.

Add mix-ins. Fold in the sprinkles and white chocolate chips until evenly spread throughout the batter.

Pan of unbaked birthday cake blondies topped with broken golden oreos.

Spread and bake. In the prepared pan, spread the batter into an even layer using a small offset spatula or knife. Gently press the broken Oreos into the top of the batter. Bake for 25-28 minutes until the edges of the blondies begin to pull away from the pan.

Pro Tip: To keep their shape, allow these birthday cake blondies to cool completely before slicing. You can also chill the blondies in the fridge to firm the butter more quickly.

Close up of birthday cake blondie square set on a flat surface surrounded by more squares and sprinkles.

How to Know When Blondies Are Done Baking

Knowing when to pull your birthday cake blondies out of the oven is key! Take them out too early, and they’ll be raw in the middle; too late, and they’ll turn dry and cakey. The sweet spot? A toothpick should come out with a few gooey crumbs or clean but not coated in raw batter. They should look and feel slightly underdone–don’t worry, the residual heat will finish the job, leaving you with perfectly fudgy, tender blondies.

Expert Tips

Use a light-colored metal pan: This is crucial. Dark pans absorb more heat, which can give you overdone edges and underbaked centers (the WORST!). I always use a light aluminum pan for the most even baking. If all you have is a dark pan, drop your oven temp by 25°F and keep a closer eye on them.
Parchment paper is your best friend: Line your pan with parchment paper with overhang on the sides so you can lift the entire slab of blondies out once cooled. This prevents those sad moments when half your blondies stick to the pan. Plus, cutting becomes SO much easier!
Mix that sugar and butter THOROUGHLY for a shiny crust: Want that gorgeous shiny top like in the photos? It’s all about aerating the batter! Whisk the sugar and eggs until they’re pale and fluffy before adding the rest of the ingredients. This simple step makes a huge difference.
DON'T OVERMIX after adding flour: I cannot stress this enough! Once you add your dry ingredients, mix JUST until combined and then STOP. Overmixing develops gluten, which gives you tough, cakey blondies instead of that dense, chewy texture we're after. When you can still see a few streaks of flour, fold in your mix-ins and call it done.

Overhead shot of birthday cake blondes cut into squares with sprinkles and Golden Oreos around.

Storage & Freezing

Room temperature: Keep your birthday blondies fresh and chewy by storing them in an airtight container at room temp for up to 3 days. Perfect for when you know they’ll be gone in no time (because, let’s be real, they will).

Refrigerate: Want to make them last a little longer? Pop them in the fridge for up to 1 week. Just let them come to room temp or give them a quick zap in the microwave before serving to bring back that soft, gooey texture.

Freeze: These blondies freeze like a dream! Wrap them tightly in plastic wrap, then place them in a freezer-safe bag or container. They’ll stay fresh for up to 3 months. When you’re ready to indulge, let them thaw at room temp or warm them up for a freshly-baked taste.

Birthday cake blondie squares set on a flat surface scattered with sprinkles and Golden Oreos.

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