My Sour Cream "Birthday Bars" Are So Melt-in-Your-Mouth Delicious

I’m a lazy baker. If there’s a shortcut to be had, I’ll take it. One of my go-to cheats is turning cookie recipes into bars; this skips the tedious step of scooping and rolling each cookie. Just press the dough into a pan, whip up a fluffy frosting, and cut the slab into squares. And that’s how these sour cream cookie bars came to be.

These cookie bars might initially look like standard sugar cookie dough, but the sour cream in the dough makes them slightly tangy, and enticingly tender and lofty like a cakey cookie (think: Lofthouse cookie). With their colorful frosting and fun sprinkles, kids and adults alike will love them. They’re also the perfect birthday treat alternative for the anti-cake people in your life.

Why You’ll Love It

• Because the sour cream acts as a leavening agent, this recipe doesn’t need baking powder or baking soda. It’s the ultimate workhorse!

• You can play around with frosting colors and the type of sprinkles. That means it’s easy to customize these cookie bars for birthdays, holidays, and any other special occasion.

Key Ingredients in Sour Cream Cookie Bars

• Sour cream: You’ll want full-fat sour cream, specifically. The cookie dough is moist, rich, and incredibly tender, thanks to the extra fat content and acid in sour cream. It also yields a nuanced tangy flavor.

• Lemon juice: Adding a squeeze of lemon to the dough boosts the tang of the sour cream and gives the bar cookies a nice brightness.

How to Make Sour Cream Cookie Bars

1. Prepare the baking pan. Line a 9×9-inch baking pan with parchment paper. The parchment sling keeps the bars from sticking to the pan and makes it easy to remove them for easy cutting.

2. Make the cookie dough. Cream softened unsalted butter and sugar together, then add room-temperature sour cream, an egg, and vanilla. The mixture may look curdled, but the flour will bring it all together. Spread the dough evenly into the pan with a rubber spatula, making sure to get into the corners.

3. Bake and cool the bars. Bake the bars until golden. You’ll get the cleanest cuts by letting the bars cool completely.

4. Finish with frosting and sprinkles. Whip up a colorful buttercream frosting to top off the bars, and use sprinkles with abandon. Make it rain, baby!

Sour Cream Cookie Bars Recipe

Between the colorful frosting and sprinkles, there’s fun in every bite.

Prep time 15 minutes

Cook time 30 minutes

Serves 16

Ingredients

For the cookie bars:

• 2 sticks (8 ounces) unsalted butter

• 1/2 cup full-fat sour cream

• 1 large egg

• 1 1/2 cups granulated sugar

• 1 tablespoon lemon juice (from 1/4 lemon)

• 2 teaspoons vanilla extract

• 1/2 teaspoon kosher salt

• 2 1/2 cups all-purpose flour

For the frosting:

• 1 stick (4 ounces) unsalted butter

• 1 pinch kosher salt

• 1 teaspoon vanilla extract

• 2 cups powdered sugar

• 1 to 2 drops food coloring gel or liquid (optional)

• 1/4 cup rainbow sprinkles (optional)

Instructions

1. Place 3 sticks unsalted butter and 1 large egg on the counter. Measure out 1/2 cup sour cream. Let everything sit at room temperature until they come to room temperature.

Make the cookie bars:

1. Arrange a rack in the middle of the oven and heat the oven to 350ºF. Line the bottom and two opposite sides of a 9x9-inch baking pan with a sheet of parchment paper long enough to hang over the sides by 1 inch to form a sling.

2. Place 2 sticks of the unsalted butter and 1 1/2 cups granulated sugar in the bowl of a stand mixer. (Alternatively, use an electric hand mixer and a large bowl). Beat with the paddle attachment on medium speed until fluffy and lightened in color, about 3 minutes.

3. Stop the mixer and scrape down the sides of the bowl with a flexible spatula. Add the sour cream, egg, 1 tablespoon lemon juice, 2 teaspoons vanilla extract, and 1/2 teaspoon kosher salt. Beat on medium speed until well-combined, about 1 minute (the mixture might look slightly curdled).

4. Stop the mixer and scrape down the sides of the bowl. Add 2 1/2 cups all-purpose flour, and beat on low speed until just fully incorporated. Transfer to the baking pan and spread it into an even layer.

5. Bake until golden-brown around the edges and lightly golden across the top, 30 to 35 minutes. Meanwhile, wash and dry the mixer bowl and paddle attachment.

6. Place the pan on a wire rack and let cool for 10 minutes. Grasping the excess parchment, lift the slab out of the pan and place on a wire rack. Let cool completely, about 45 minutes. Meanwhile, make the frosting.

Make the frosting:

1. Place the remaining 1 stick unsalted butter and 1 pinch kosher salt in the mixer bowl. Beat with the paddle attachment on medium speed until lightened in color and creamy, scraping down the sides of the bowl as needed, about 2 minutes total. Add 1 teaspoon vanilla extract and beat until combined.

2. Turn the mixer to low speed. Add 2 cups powdered sugar in two additions and beat until completely incorporated. Add 1 to 2 drops food coloring gel or liquid if desired and beat until evenly colored, stopping to scrape down the sides of the bowl as needed.

3. Transfer the frosting onto the cookie slab and spread it into an even layer with an offset spatula. Top with 1/4 cup sprinkles if desired. Let sit at room temperature for at least 30 minutes to let the frosting stiffen. For the cleanest slices, refrigerate the assembled bars for 20 minutes before slicing.

4. Grasping the excess parchment, transfer the slab onto a cutting board. Trim the edges of the slab if desired, then cut into 16 pieces.

Recipe Notes

Make ahead: The bars can be baked up to 1 day ahead, but it’s best to frost the day you are serving them. Cover when cool and store at room temperature.

Storage: Leftovers can be stored in an airtight container layered with wax or parchment paper for up to 3 days at room temperature or 1 week in the refrigerator. The bars can also be wrapped in aluminum foil and frozen for up to 3 months. Thaw at room temperature before serving.