Erin’s Recipe Rundown
These easy gluten-free brownies start with a reliable boxed mix but taste far from basic. A generous peanut butter swirl and a rich, fudgy crumb elevate the brownies into something special. They’re my go-to when I want a quick, crowd-pleasing dessert that saves time without sacrificing flavor.
Why you’ll love them: The brownies are deeply chocolatey and fudgy, with ribbons of creamy peanut butter throughout. They bake up consistently when you follow a few key tips, and the recipe comes together in a single bowl for minimal cleanup.
Top tips: Don’t overbake—pull the pan when the center still has moist crumbs for a perfect fudgy texture. Warm the peanut butter briefly so it drops and spreads easily without dragging the batter. For a nut-free variation, sunflower seed butter works well.
xoxo erin
This post was created in partnership with King Arthur Baking Company.
Ingredients You’ll Need
Below are notes on the key ingredients for making these gluten-free peanut butter brownies. See the recipe card further down for exact measurements and a printable ingredients list.
- Gluten-free cake mix: A quality gluten-free brownie mix gives the best results—look for one labeled for fudgy brownies so the texture stays dense and moist.
- Peanut butter: Use creamy peanut butter for smooth, even swirls. If the peanut butter is very thick, warm it a few seconds in the microwave so it drops from a spoon easily. For a nut-free option, substitute sunflower seed butter.
- Chocolate chips: Semi-sweet or dark chips add extra chocolate flavor and pockets of melty texture. Choose dairy-free chips if you need the recipe to be dairy-free.
How to Make Gluten-Free Peanut Butter Brownies
Here’s an overview of the process. Follow the recipe card below for precise measurements and baking times.
1. Combine the wet ingredients: Whisk melted butter, water, and eggs until smooth and glossy. This helps ensure an even, fudgy batter.
2. Add the mix and chocolate: Stir in the boxed brownie mix and the chocolate chips just until incorporated. The batter should be thick and fudgy—avoid overmixing.
3. Add peanut butter dollops: Spread the batter into a prepared pan. Warm the peanut butter slightly if needed, then drop small spoonfuls evenly over the top.
4. Swirl to marble: Use a toothpick or the tip of a knife to gently swirl the peanut butter into the batter, creating a marbled effect. Aim for pretty ribbons rather than full incorporation.
5. Bake and cool: Bake until a toothpick inserted in the center comes out with moist crumbs but no raw batter. The center should wobble slightly when you pull the pan from the oven—this ensures fudginess. Let the brownies cool at least 15 minutes before slicing.
Gluten-Free Box-Mix Peanut Butter Brownies
Erin Collins
15 mins
40 mins
16
Ingredients
- 1 box King Arthur Flour Gluten-Free Fudge Brownie Mix
- 1/2 cup butter, melted
- 2 tablespoons water
- 2 large eggs
- 1 cup chocolate chips
- 1/3 cup peanut butter
Instructions
- Preheat the oven to 350°F (reduce to 325°F if using a glass or dark metal pan). Grease an 8″ square or 9″ round pan and line with parchment.
- Whisk together the melted butter, water, and eggs until smooth. Stir in the brownie mix, then fold in the chocolate chips. Spread the batter evenly in the prepared pan.
- Drop spoonfuls of peanut butter across the top of the batter, spacing them evenly. If the peanut butter is thick, warm it briefly so it drops easily. Use a toothpick or knife tip to swirl for a marbled pattern.
- Bake 35–40 minutes in a light metal pan, or 30–35 minutes in a dark metal or glass pan. A toothpick inserted into the center should come out with moist crumbs but no raw batter. Allow brownies to cool at least 15 minutes before slicing.
Notes
Gluten-free: This recipe is adapted to be gluten-free using a gluten-free brownie mix.
Dairy-free: Substitute dairy-free butter and dairy-free chocolate chips to make the brownies dairy-free.
Nut-free: Replace peanut butter with sunflower seed butter for a nut-free alternative.
Make-ahead: Brownies can be baked up to 2 days in advance. Once cooled, store in an airtight container at room temperature.
Storage and freezing: Store at room temperature for up to three days in an airtight container. To freeze, cut into squares and freeze in a sealed bag or container for up to 2 months; thaw at room temperature before serving.
Nutrition
| Carbohydrates: 29 g
| Protein: 4 g
| Fat: 14 g
| Sugar: 21 g