Easy recipes for dessert are my lifeblood. Seriously. And these frosted funfetti birthday cake cookie bars are a true labor of love.

Because I screwed them up twice before getting them right. Bah ha ha.

I’m special like that.

But in all seriousness, I have eaten so many cookie bars in the past two days I could die. They are so delicious, though, even in their failed form.

The first batch came out ridiculously overcooked. My oven has a mind of its own, and since it’s about as old as I am…yeah. Sad face.

The second batch came out slightly overcooked, as my oven refuses to sit at any temperature I actually want it to be, and it also fell flat because there was too much moisture.

After additional adjustments, I am happy to say that this is now one of my bestest easy recipes for dessert. I sent a photo off to my husband via Facebook and he called me literally ten seconds after seeing it, telling me I needed to bring them to his clinic ASAP before his coworkers killed him.

Bah ha ha.

I couldn’t oblige, though, because I have to go pick up Delaney from her after-school program. It’s a sad day in Rudy’s life, fo realz.

I baked this bad boy in my trusty 13×9 inch pan, and instead of using a funfetti cake mix, I mixed in my own sprinkles, which I am definitely a sucker for the little round nonpareils. Remember my fairy bread? Yeah, same stuff. Love it.

I also added white chocolate chips. I mean, how could I not? It just doesn’t seem like a cookie bar without some kind of chocolate chip.

And of course, I frosted these delicious noms, again, because how could I not? You can either grab your favorite container of frosting from the store, or use my buttercream recipe below. Either way, delicious.

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Frosted Funfetti Birthday Cake Cookie Bars

Prep Time 10 minutes

Cook Time 35 minutes

Total Time 45 minutes

Servings 16

Author Karly

Ingredients

For the Cookie Bars

• 1 1/2 C All-Purpose Flour
• 1 1/2 C Vanilla/White Boxed Cake Mix
• 1 tsp Baking Soda
• 3/4 C Unsalted Butter, softened
• 1/2 C White Granulated Sugar
• 1/2 C Light Brown Sugar, packed
• 1 Large Egg, room temperature
• 1 1/2 tsp Vanilla Extract
• 3/4 C White Chocolate Chips
• 1/2 C Sprinkles

For the Buttercream Frosting

• 1 C Unsalted Butter, softened
• 2 Tbsp Light Corn Syrup
• 2 tsp Vanilla Extract
• Pinch of Kosher Salt
• 5 C Powdered Sugar
• 1/2 C Heavy Whipping Cream

Instructions

For the Cookie Bars

• Heat oven to 300 degrees. Grease a 13x9 inch pan and set aside.
• In a large bowl, whisk together the flour, dry cake mix, and baking soda. Set aside.
• In the bowl of a stand or handheld mixer, add the butter and sugars, then beat with a paddle attachment on medium until smooth and slightly fluffy, around 3 minutes. Add the egg and beat on high for 1 minute, then add the vanilla extract and beat on high until combined. Add the flour mixture and beat on low until just combined. Mix in the white chocolate chips and sprinkles on low until evenly distributed.
• Scoop batter into 13x9 inch pan and press down by hand until evenly distributed*. Bake for 35-40 minutes, or until golden brown on top and a toothpick inserted into the center comes out mostly clean. Place on a cooling rack and allow to cool completely before frosting.

For the Buttercream Frosting

• In a large mixing bowl, beat together the butter, light corn syrup, vanilla, and kosher salt until light and fluffy, around 5 minutes. Slowly beat in the powdered sugar in batches, adding the heavy cream as necessary to thin the buttercream. Once the desired consistency is reached, spread on cookie bars. Reserve any remaining frosting in an airtight container in the fridge for up to 2 weeks.

Notes

*Because I hate high lips around the edge of the pan, I usually mound the dough higher in the middle and leave a thin edge around the pan. That way, as it bakes and spreads, it evens out better in the pan.

Nutrition Disclaimer

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Course Dessert