Gluten Free Peanut Butter Cookie Bars

These soft and chewy gluten-free peanut butter cookie bars are beyond easy to make and full of peanut buttery goodness. Imagine super soft peanut butter cookies with an abundance of chocolate but baked in a loaf pan. A recipe your whole family will love. This recipe comes together in a pinch and can easily be doubled if you would like to bake them in an 8-inch 9-inch square pan.

Why you will love this recipe? The gluten-free cookie bars don't require any chill time (unlike gluten-free chocolate chip cookies) and are the perfect recipe if this is your first time baking gluten-free. Also - this recipe is very adaptable. You can mix up the add-ins and create your own new favorite cookie bar.

If you love a good bar cookie make sure to check out my Gluten Free Blondies and my Gluten Free Strawberry Crumble Bars. More in the mood for a cookie? Take a peek at my Oreo loaded chocolate chip cookies.

Recipe Ingredient Notes

Gluten-Free Flour: I have tested this recipe with my own gluten-free flour blend, King Arthur Measure for Measure and Bob’s Red Mill 1-to-1. Both flour blends produced a tender, moist crumb and exceptional flavor. I am not saying other brands will not work in this recipe. I just have not tested them in this application. Flours blends used to develop this great recipe do contain xanthan gum.

Peanut Butter: The key ingredient to making Gluten-Free Peanut Butter Chocolate Chip Cookie Bars is definitely peanut butter. I prefer baking with “conventional” peanut butter such as Jif or Skippy. Conventional peanut butter is made with fully hydrogenated vegetable oils, which help stabilize the peanut butter and prevent it from separating. In my opinion, it’s more reliable in baking than natural peanut butter (which is perfect for snacking!). Creamy peanut butter or crunchy peanut butter will work in this recipe.

Brown Sugar: The brown sugar used in this recipe gives them a darker, richer flavor due to the molasses. The flavor is very similar to Toffee. You can use either dark or light brown sugar.

Step by Step Instructions

This recipe for gluten-free peanut butter bars comes together in less than 15 minutes. All you need are a small sauce pan or microwave-safe bowl to melt the butter, a large bowl, and a standard loaf pan. You will also need a flexible rubber spatula and a whisk. No need to bring out the stand mixer.

Step 1: Preheat your oven to 350F and arrange the wire rack in the oven in the middle. Line a standard loaf pan (8.5 x 4.5 inches) with parchment paper. Make sure to leave some overhang on the sides of the pan to remove the peanut butter bars without any issues once baked and fully cooled. (If you use little binder clips to keep parchment paper in place while assembling your peanut butter cookie bars, please remove them before baking!)

Step 2: In a small pot, over medium heat, melt the butter. If you like you can brown the butter which will give the peanut butter bars a rich and nutty note. (Find detailed instructions on how to brown butter here: How to brown butter) Allow the butter to cool for 5 minutes. Alternatively, you can also melt the butter in the microwave.

Step 3: Combine gluten-free flour, baking powder, and kosher salt in a separate medium bowl and set aside.

Step 4: In a large bowl combine the cooled but still fluid butter, peanut butter, vanilla extract, and brown sugar and whisk until smooth. The warmth of the melted butter will help melt the peanut butter.

Step 5: Add the whole egg and whisk until fully incorporated.

Step 6: Once the wet ingredients are fully combined, fold in the dry ingredients using a flexible rubber spatula. This will be easier with a spatula than a whisk.

Step 7: Fold in chocolate chips or other add-ins you may be using (I use Mini Peanut Butter Cups and Dark Chocolate Chips) Add the cookie dough to the prepared pan, smoothing out the top with the back of a spoon or an offset knife in an even layer.

Step 8: Top with additional chocolate if you like and bake at 350F for 23-25 minutes. The gluten-free peanut butter cookie bars are done when the edges are set and golden brown and a toothpick or skewer inserted into the center comes out mostly clean.

Step 9: Remove the pan from the oven, sprinkle with some flaky sea salt if you like, and allow the cookie bars cool in the pan for about an hour before removing and cutting.

Store any leftovers you may have in an airtight container at room temperature for 3-5 days.

Variations of Peanut Butter Cookie Bars

There are endless possibilities to change up this recipe for gluten-free peanut butter cookie bars. Here are a few ideas.

Almond Butter: Swap out the peanut butter for almond butter or sunflower seed butter.

Vegan Peanut Butter Cookie Bars: Replace the butter used with your favorite non-dairy butter (I do not recommend coconut oil) and use 3 tablespoons of aquafaba or a flax-egg to replace the egg used in this recipe. To make a flax egg combine 1 Tbsp flaxseed meal (ground raw flaxseed) and 2 .5 Tbsp water and allow to sit for 5 minutes before using in this recipe.

Change up the Candy: Here are a few gluten-free candy ideas you could use in this recipe: Cadbury Mini Chocolate Eggs, Snickers, Plain M&M's, Peanut M&M's, Rolo, Heath Bars, Cadbury Caramel Eggs, Butterfingers....

Add Nuts: Replace 50 grams of the add-ins with chopped-up, salted peanuts for that extra peanut butter flavor.

Chocolate: Milk, Dark, Semi-Sweet, Reeses's Peanut Butter Chips, Chocolate Chips, Chocolate Chunks, your favorite artisan chocolate bar... anything goes when it comes to this recipe.

FAQ about Gluten Free Peanut Butter Cookie Bars

Can I make this recipe with All Purpose Flour?
To make this recipe with "regular" all purpose flour please replace the gluten-free flour with 140 grams of AP Flour.

Can I make this recipe without Peanut Butter?
I don't recommend leaving out an important ingredient like peanut butter in this recipe. For a bar cookie without peanut butter, please check out my Gluten Free Blondies

Can I make this recipe vegan?
Replace the butter used with your favorite non-dairy butter (I do not recommend coconut oil) and use 3 tablespoons of aquafaba or a flax-egg to replace the egg used in this recipe. To make a flax egg combine 1 Tbsp flaxseed meal (ground raw flaxseed) and 2 .5 Tbsp water and allow to sit for 5 minutes before using in this recipe.

Can I freeze peanut butter cookie bars?
Once fully cooled these gluten-free bar cookies freeze wonderfully. You can freeze them sliced or unsliced. Make sure to store them in an airtight container and freeze them for up to 3 months.