No need for a mix for these extra tender gluten free sugar cookie bars made with sour cream. Instead of frosting, the vanilla sugar on top creates an ultra-thin crackling crust.
These sugar cookie bars aren't just basic sugar cookies in bar form. Not that I'm throwing shade; I love basic sugar cookies.
From drop cookies to cutout cookies, vanilla to chocolate to maple-flavored, I adore them all. But these bars just aren't essentially the same type of recipe but baked in a pan and sliced into bars.
They're softer and more tender, with a mild tang from all that sour cream baked into the cookie dough. They aren't burdened by the need to hold a shape and clean lines, so they devote themselves fully to flavor.
How to make vanilla sugar
Sugar cookie bars are often served with a thick layer of buttercream frosting. I guess the inspiration is the Lofthouse-style cutout sugar cookies that have that gorgeous thick layer of frosting.
But this gluten free sugar cookie bars recipe is more delicate in texture. Along with the extra tender cookie bar, they have a razor-thin layer of vanilla sugar on top that bakes into a satisfying crackle topping.
To make vanilla sugar, place granulated sugar and as many vanilla bean seeds as you're willing to spare in a food processor. Pulse a few times.
I use the seeds from 1/2 of a vanilla bean for each 1/2 cup of granulated sugar. That's a relatively generous amount, so feel free to use fewer seeds since vanilla is just. so. expensive.
The mixture will clump, but it will still keep for a long time at room temperature. I store it in a sealed glass jar and press it with a spoon to break up clumps before using it.
Be sure to keep it in a glass container, not plastic. Plastic will absorb the aroma rather than preserve it in the sugar. And keep the jar covered, to keep that lovely smell contained.
Make these sugar cookie bars thinner or thicker
I've made these tender, flavorful cookie bars both about 1-inch thick, and about 1/2-inch thick. I prefer them thicker, but I've provided instructions for how to do either.
Regardless of thickness, doneness can't be determined visually or with your hands. You can't press gently in the center of the pan without cracking the thin sugar crust. And you can't see underneath the crust to determine if it's set in the center.
In the photos here, the bars are nice and thick, with a generous crackly vanilla sugar crust. If you'd like them thick like that, just make them in a 9-inch square pan.
The baking time is about 30 minutes, or until a toothpick inserted in the center comes out clean.
To make thinner bars, you'll need a 9-inch x 13-inch x 2-inch pan. The baking time is about 22 minutes.
You can't use a jelly roll pan, with sides that are less than 2-inches, because it doesn't have enough volume. You'll need something with higher sides.
Be sure your oven temperature is no higher than 350°F as indicated by a separate thermometer. A higher temperature will burn the underside in the center before the rest of the cookie dough has finished baking.
For cutout cookies
If you're looking for cutout cookies that you can make into fancy shapes, I have plenty of other recipes for that. Have a look at our recipe for soft gluten free cutout sugar cookies.
For a tangier version that is more similar in taste to these sour cream sugar cookie bars, try our recipe for gluten free cream cheese cutout sugar cookies. For the tenderness and taste of the cookie alone, that recipe can't be beat if you're in need of a shaped cookie.
Ingredients and substitution
In place of the butter in this recipe, try using vegan butter. My favorite brands are Melt and Miyoko's Kitchen.
In place of the sour cream, you can use plain Greek yogurt (dairy or nondairy). You cannot use plain yogurt of any kind that is the “regular” thickness, since that has too much moisture.
If you use an ingredient like plain “regular” yogurt with too much moisture in it, the recipe won't work—and you can't say I didn't warn you! Plus, I will continue to push back on comments that blame me for errors that were not recipe-related, but execution-related.
If you have a nondairy sour cream brand that you love, you can use that, too. Just be sure it's the proper thickness, and that you like the taste of it, since baking only intensifies the flavor.
There is one egg and one egg yolk in this recipe. You should be able to replace each of those with an appropriate amount of a “chia egg.”
In place of the full egg, use 1 full chia egg. In place of the yolk, use just one half. The total would be 1 1/2 tablespoons ground white chia seeds + 1 1/2 tablespoons lukewarm water, mixed and allowed to gel.
Sour Cream Gluten Free Sugar Cookie Bars
2 1/4 cups (315 g) all purpose flour gluten free flour (I used Better Batter)
1 teaspoon xanthan gum (omit if your blend already contains it)
3/4 teaspoon baking powder
1/2 teaspoon baking soda
1/4 teaspoon kosher salt
12 tablespoons (168 g) unsalted butter, at warm room temperature
3/4 cup (150 g) granulated sugar
1 egg (50 g, weighed out of shell) + 1 egg yolk (25 g) at room temperature, beaten
1 teaspoon pure vanilla extract
1 1/2 cups (173 g) confectioners’ sugar
3/4 cup (192 g) sour cream, at warm room temperature
Vanilla sugar, for sprinkling (2 to 3 tablespoons) (See Recipe Notes).
For the vanilla sugar
To make vanilla sugar, place granulated sugar and as many vanilla bean seeds as you’re willing to spare in a food processor. Pulse a few times.
In place of vanilla sugar, you can of course use plain granulated sugar on top of the bars—or no sugar at all. If you’re partial to a buttercream frosting on your bars, use that!
Grease and line a 9-inch square baking pan or a 9-inch x 13-inch x 2-inch baking pan and set it aside. Preheat your oven to 350°F.
In a medium-sized bowl, place the flour, xanthan gum, baking powder, baking soda, and salt, and whisk to combine well. Set the dry ingredients aside.
In the bowl of a stand mixer fitted with the paddle attachment or a large bowl with a handheld mixer, place the butter and granulated sugar, and beat on medium-high speed until light and fluffy (about 5 minutes).
Add the egg, egg yolk, and vanilla and beat to combine. Add the confectioners’ sugar, and beat until smooth, then the sour cream and beat again until smooth. Add the dry ingredients and mix until just combined. The cookie dough will be thick but relatively soft.
Transfer the cookie dough to the prepared baking pan. Using a moistened spatula, spread it into an even layer in the prepared pan. Sprinkle the top evenly with a thin layer of vanilla sugar (about 3 tablespoons). Turn the pan toward each side to distribute the sugar evenly over the top.
Place the pan in the center of the preheated oven and bake until set all the way to the center and a toothpick comes out clean (about 30 minutes for the square pan; about 22 minutes for the rectangular pan). Allow to cool completely in the pan before slicing into squares and serving.