Birthday Cake Blondies for a Fuss Free Birthday Treat
If you’re looking for a birthday cake that’s way easier to make than cake, these birthday cake blondies have you covered. You can make them without a mixer, and bake them in a toaster oven for even less fuss. That they make incredible brownie sundaes with a scoop of No-Churn Ice Cream and a drizzle of Hot Fudge Sauce or Dulce De Leche makes them the perfect Summer birthday treat.
| Taste | Texture |
| White chocolate, buttery | Chewy, fudgy |
| Active time | Total time | Yield | Difficulty |
| 15 minutes | 35 minutes | 9 large blondies or 16 small blondies | Easy |
Birthday Cake Blondies aka Funfetti Blondies are a happy marriage between a decadent brown butter blondie and a funfetti cake. Like my Confetti Sugar Cookies, the rainbow sprinkles bring a lot of whimsy to these bars AND add some extra color without having to spend time decorating afterwards.
Why This Recipe Works

- Brown Butter = Big Flavor: As in all of my Brown Butter Blondies, taking the extra step of browning the butter adds caramel undertones to the bars that you wouldn’t get from simply melting the butter.
- The Decoration is Done Before Baking: I rarely have time to decorate cakes, and I imagine you’re in the same boat. It’s always been my philosophy that decorating should be as easy as possible, and if it can be done before baking, all the better. These bars go in the oven pretty and they come out pretty without any extra decorating work. Win win!
- You Really Can Bake These in a Toaster Oven: My toaster oven works overtime in the Summer to keep the kitchen cool. Anytime you can bake in a small oven, it’s a win.
- Toasty flavors: In addition to the bars which already have a toasty caramel flavor, the white chocolate on top picks up a little extra color. If you’ve ever had caramelized white chocolate, you already know this is a good idea.

Ingredients for Birthday Cake Blondies
Brown Butter Blondie Base + Festive Mix-Ins
- Butter
- Powdered sugar
- Dark brown sugar
- Baking powder
- Salt
- 1 large whole egg plus 1 egg yolk
- Vanilla paste or vanilla extract
- All-purpose flour
- White Chocolate Chips
- Rainbow Sprinkles
Equipment Needed
- 8×8 pan, a disposable square foil pan or a Toaster Oven Pan
- Double boiler or a bowl and a 1 qt. pot
- Whisk
- Parchment
The answer always is whatever you have, but I prefer dye free sprinkles in the classic rod-shaped “jimmy” shape. I’ve noticed that there is less color bleed in the batter from the naturally colored sprinkles and they have less of a strong flavor you can sometimes get from regular rainbow sprinkles. These days you can find even store brands of natural colored sprinkles. I like Watkins natural sprinkles and Supernatural sprinkles plus Simple Truth Rainbow Sprinkles from my local King Soopers (Kroger).
How to Make Funfetti Blondies Step By Step








- Line the bottom of an 8×8 pan with a parchment sling (2 pieces of parchment that cover the bottom of the pan and go up the sides, meeting in the middle of the pan at right angles to each other).
- Make brown butter: Melt the butter over low heat in a small pan until the foam starts to subside and there are brown flecks in the bottom of the pan. On low heat, this will take about 10 minutes, though you can heat it on medium heat in about 5 minutes. Set it in a mixing bowl to cool.
- Warm the sugars and eggs: Fill the bottom of a double boiler with about 1″ of water, and then bring it to a boil. Use a whisk to mix the sugars, baking powder, salt, whole egg and the egg yolk in the top of the double boiler . Lower the water to simmer, then set the top pot over the water, stirring constantly for about 4 minutes. In this time, the mixture will get thinner, paler, and all of the sugar will dissolve.
- Add the sugar to the butter: Whisk the egg/sugar mix into the butter. If it splits, keep whisking. As it cools, it will come back together. Allow the butter mix to cool until it’s thick and no longer warm to the touch. It will be noticeably thicker and glossy.
- Add the flour and mix-ins: Fold in the flour, 4 tablespoons of the sprinkles, and all but a few of the white chocolate chips with a baking spatula until the flour disappears.
- Decorate the Top: Smooth the batter into the prepared pan. Sprinkle the remaining tablespoon of sprinkles and the rest of the white chocolate chips on top of the batter.
- Bake for 16-18 minutes until the edges are browning and the middle is no longer jiggling.
- Cool the bars completely before cutting.
How to Make Party-Worthy Birthday Cake Blondies

- Don’t Overbake: Nobody likes dry blondies! Start checking the bars at about 14 minutes. Shake the pan gently, and if it doesn’t move around, they are done. There’s no need to bake them a second longer!
- Avoid Color Bleed: As I alluded to above, I’ve noticed that there’s less color bleed from naturally-colored sprinkles. That being said, if you add in the white chocolate and sprinkles WITH the flour, the flour will coat the sprinkles, keeping any color bleed to a minimum. If the color in your bars looks a little smeared, they will still taste delicious, but aesthetically, it’s nice to see the sprinkles, not the dye.
- Bake Them in a Disposable Pan: If you’re having your birthday celebration outside your house, bake your bars in a disposable foil pan for easy transport and cleanup. You can cut them ahead of time and even freeze them to make your party as easy as possible.
Awesome Things to Serve with Your Birthday Cake Blondies
Birthday Cake Blondies
- Total Time: 33 minutes
- Yield: 16 small blondies 1x
Description
These bars have all the chewy butterscotch flavor of classic Brown Butter Blondies with the festive additions of white chocolate chips and rainbow sprinkles. They’re a great cake alternative for an easy birthday party treat, especially if you top it with some no-churn ice cream.
Ingredients
- Cooking Spray for the pan
Birthday Cake Blondies Batter
- 1 stick butter (113 g)
- 1/3 cup powdered sugar (40 g)
- 1/3 cup dark brown sugar (66 g)
- 1/2 tsp baking powder
- 1/2 tsp salt
- 1 large whole egg plus 1 egg yolk
- 1 tsp vanilla paste
- 1 cup all-purpose flour (130 g)
- 1 cup white chocolate chips (170 g)
- 5 Tablespoons rainbow sprinkles
Instructions
Preheat the oven to 350F (180 C).
Prep the Pan
- Lightly spray an 8″x8″ pan with cooking spray.
- Cut a piece of parchment to line the bottom and sides of one side. Spray over the top of this piece of parchment, then cut another one to go across the remaining 2 sides of the pan.
Brown the Butter
- Melt the butter over low heat in a small pan until the foam starts to subside and there are brown flecks in the bottom of the pan. On low heat, this will take about 10 minutes.

Dissolve the Sugar
- While the butter is browning, fill the bottom of a double boiler with about 1″ of water, then bring it to a boil.

- Use a whisk to mix the sugars, baking powder, salt, whole egg and the egg yolk in the top of a double boiler.
- Lower the water to simmer, then set the top pot over the water, stirring constantly for about 4 minutes. In this time, the mixture will get thinner, paler, and all of the sugar will dissolve.

- Once the butter has browned, set it in a bowl to cool slightly.

- Whisk the egg/sugar mix into the butter. If it splits, keep whisking. As it cools, it will come back together. Add in the vanilla.

- Allow the butter mix to cool until it’s thick and no longer warm to the touch. It will be noticeably thicker and glossy.
Add the Flour and Mix-Ins
- Fold in the flour, 4 tablespoons of the sprinkles, and all but a few of the white chocolate chips with a baking spatula until the flour disappears.

- Smooth the batter into the prepared pan.
Finish the Blondies
- Sprinkle the remaining tablespoon of sprinkles and the rest of the white chocolate chips on top of the batter.

- Bake for 16-18 minutes until the edges are browning and the middle is no longer jiggling.
- Cool the bars completely before cutting into 9 large bars or 16 smaller bars.

- Prep Time: 15 minutes
- Cook Time: 18 minutes
- Category: Bar cookies
- Method: Oven, Stovetop
- Cuisine: American






















