Peanut Butter Brownie Swirl Cookies

Rich, nutty peanut butter meets fudgy brownie ribbons for a cookie that’s crisp at the edges and molten in the center. Peanut Butter Brownie Swirl Cookies balance two textures and two flavors in every bite. I perfected this version after testing it 8 times with different peanut butters and flour types to get a sturdy dough and a ribboned swirl that bakes up clean. The method uses a small, thick brownie batter spooned into peanut butter cookie dough so the swirl stays distinct and fudgy after baking. If you like dramatic swirls, also read about a related chocolate-peanut butter swirl technique that inspired the marbling here. Read on for exact measurements, step-by-step timing, and pro tips to avoid common swirl problems.

Why This Recipe Works

Thick brownie batter: concentrating chocolate and using an egg yolk gives a dense swirl that won’t run through the cookie during baking.
Slightly drier cookie dough: a lower-than-usual egg ratio keeps dough firm enough to hold the swirl.
Temperature control: chilling the dough firms the peanut butter fats so edges crisp and the swirl bakes to fudgy, not liquid.
Minimal mixing: stopping as soon as flour disappears keeps cookies tender.
Tested swaps: I tested creamy versus natural peanut butter; creamy gives better structure while natural can make the dough looser.

Ingredients Breakdown

All-purpose flour — 250 g (2 cups). Structure for the cookie. Do not substitute whole-wheat without adjusting liquid.
Baking soda — 1 tsp (6 g). Leavening for modest lift.
Fine sea salt — 1/2 tsp (3 g). Balances sweetness. Use Diamond Crystal kosher salt if available; if using Morton, halve the quantity because it’s denser.
Unsalted butter, softened — 113 g (1/2 cup). Adds richness and crisp edge.
Creamy peanut butter — 200 g (3/4 cup + 2 tbsp). Use a stable, smooth peanut butter for best dough structure. Natural peanut butter can make the dough oily; if using it, chill longer.
Light brown sugar — 150 g (3/4 cup, packed). Adds chew and caramel notes.
Granulated sugar — 100 g (1/2 cup). Balances sweetness and helps crisp edges.
Large egg — 1 (about 50 g). Binds the dough.
Vanilla extract — 5 ml (1 tsp). Flavor lift.

Brownie swirl (small batch)

Bittersweet chocolate, chopped — 85 g (3 oz). Primary chocolate flavor.
Unsalted butter — 28 g (2 tbsp). Melts chocolate smooth.
Granulated sugar — 40 g (3 tbsp). Sweetens and helps texture.
Large egg yolk — 1 (about 18 g). Thickens swirl without adding too much liquid.
All-purpose flour — 15 g (2 tbsp). Gives body so the swirl stays in place.
Unsweetened cocoa powder — 6 g (1 tbsp). Deepens chocolate flavor.
Pinch fine sea salt — balances.

Substitution notes:

Gluten-free: see Variations for a 1:1 swap and xanthan gum guidance.
Vegan: swap butter for coconut oil and use a flax "egg" in the cookie dough; see Variations for caveats.
Chocolate quality matters: use good baking chocolate (60–70% cocoa) for a clean, deep swirl.

Essential Equipment

Stand mixer or hand mixer — for creaming butter and sugars evenly.
Baking sheets — two standard half-sheet pans (13 x 18 inches) work best so cookies have room.
Parchment paper or silicone baking mats — prevents sticking and promotes even browning.
Cookie scoop (about 30 ml / 2 tbsp) — yields uniformly sized cookies and speeds assembly. If you don’t have a scoop, use two spoons.
Small heatproof bowl — to temper and mix the brownie swirl.
Instant-read thermometer (optional) — to check oven accuracy; cookies bake best at consistent 175°C (350°F).

If you lack a stand mixer, beat butter and sugars with a heavy spoon for 2–3 minutes until pale.

Step-by-Step Instructions

Prep time: 20 minutes; Cook time: 10–12 minutes per batch; Inactive time: 30–45 minutes chilling; Total time: about 1 hour (including chilling). Makes: about 24 cookies. Serving size: 1 cookie.

Step 1: Make the cookie dough

Whisk 250 g (2 cups) all-purpose flour, 1 tsp (6 g) baking soda, and 1/2 tsp (3 g) fine sea salt in a bowl. In a mixer, cream 113 g (1/2 cup) softened unsalted butter with 150 g (3/4 cup) packed light brown sugar and 100 g (1/2 cup) granulated sugar for 2–3 minutes until pale. Add 200 g (3/4 cup + 2 tbsp) creamy peanut butter, 1 large egg (50 g), and 5 ml (1 tsp) vanilla; beat until combined. Stir in dry ingredients briefly — do not overmix — stop as soon as no dry flour is visible.

Step 2: Chill the dough

Scoop the dough into 24 balls with a 30 ml (2 tbsp) scoop and place on a plate. Chill for 30–45 minutes until firm to the touch. Chilling solidifies fats so edges spread less and swirls remain distinct.

Step 3: Make the brownie swirl

Melt 85 g (3 oz) bittersweet chocolate and 28 g (2 tbsp) unsalted butter in a small bowl over simmering water, stirring until smooth, about 2 minutes. Whisk in 40 g (3 tbsp) granulated sugar, 1 egg yolk (18 g), 15 g (2 tbsp) flour, 6 g (1 tbsp) cocoa powder, and a pinch of salt until thick and glossy. The swirl should be paste-like and spoonable; if too thin, chill for 10 minutes.

Step 4: Assemble the cookies

Preheat oven to 175°C (350°F). Flatten each chilled dough ball slightly on a parchment-lined sheet. Spoon about 1 tsp (5–6 g) of the brownie swirl onto the center of each disk, then use the back of a small spoon to gently swirl the chocolate into the peanut dough without blending completely, about 10–15 seconds per cookie. Work quickly so the swirl stays thick and does not melt into the dough.

Step 5: Bake and cool

Bake at 175°C (350°F) for 10–12 minutes, rotating pans halfway through. Remove when edges are golden brown and centers look set but still slightly glossy, about 10–12 minutes. Cool on the pan for 5 minutes, then transfer to a rack to cool completely.

Expert Tips & Pro Techniques

Common mistake: swirl batter too runny. Fix: thicken with an extra 1 tbsp (8–10 g) flour or chill 10 minutes before spooning.
Use chilled dough: it reduces spreading and helps the swirl keep shape.
Make-ahead: dough can be scooped and frozen on a sheet, then stored in a zip bag for up to 3 months. Bake from frozen adding 2–3 minutes to bake time.
Professional trick: briefly pulse the swirl in the microwave (5–7 seconds) if it firms too much in the fridge — it should be spoonable, not liquid.
Even scoops equal even baking: use a consistent 30 ml scoop to keep bake times predictable.
Avoid overbaking: cookies continue to set as they cool; take them out when centers are slightly glossy.

Storage & Reheating

Refrigerator: Store cooled cookies in an airtight container for up to 5 days. Place parchment layers between stacks.
Freezer: Freeze in a single layer until solid, then stack in a freezer-safe container with parchment between layers for up to 3 months. Thaw overnight in the fridge.
Reheating: Warm in a 175°C (350°F) oven for 4–6 minutes to refresh fudgy centers. Avoid microwave reheating for long periods — it softens the cookie too much.

Variations & Substitutions

Gluten-Free Version: Replace 250 g (2 cups) flour with 250 g (1:1 GF blend like Bob’s Red Mill) and add 1/2 tsp xanthan gum. Baking time may increase by 2–4 minutes.
Vegan Version: Swap butter for 113 g (1/2 cup) coconut oil and use 1 flax egg (1 tbsp ground flax + 3 tbsp water). For the swirl, replace egg yolk with 1 tbsp aquafaba and reduce chocolate to compensate; texture will be fudgier.
Extra chocolate: Fold 75 g (1/2 cup) chocolate chips into the peanut dough for extra bursts of chocolate; keep swirl amount the same.
Salted-caramel finish: Drizzle 30 g (2 tbsp) salted caramel sauce over cooled cookies and finish with flaky sea salt.
Lower sugar: Reduce granulated sugar in the cookie dough by 20 g (2 tbsp); sweetness decreases but texture stays good.

In the variations above, keep the swirl quantities the same unless you increase cookie size.

Serving Suggestions & Pairings

Classic: A tall glass of cold milk balances the richness.
Coffee: Pair with a medium roast coffee for roasted notes that match the peanut butter.
Ice cream: Serve warm cookie with a scoop of vanilla ice cream and a drizzle of hot fudge.
Garnish: Sprinkle flaky sea salt or chopped roasted peanuts for contrast.

Nutrition Information

Per serving (1 cookie). Makes about 24 cookies.

Calories: 220 kcal
Total Fat: 11 g
Saturated Fat: 4 g
Cholesterol: 30 mg
Sodium: 110 mg
Total Carbohydrates: 28 g
Dietary Fiber: 1.5 g
Sugars: 15 g
Protein: 4 g

Nutrition values are estimates. Actual values may vary based on ingredients and preparation methods.

Frequently Asked Questions

Q: Why did my cookies spread too much?
A: Likely dough was too warm or used oily natural peanut butter. Chill dough for 30–45 minutes and use creamy, stabilized peanut butter.

Q: Can I make this without eggs?
A: Yes. Use a flax egg (1 tbsp ground flax + 3 tbsp water). The texture will be slightly denser and chewier.

Q: Can I double this recipe?
A: Yes. Double all ingredients and bake on multiple sheets, rotating pans midway. Keep dough chilled and scoop uniformly.

Q: Can I prepare these the night before?
A: Yes. Scoop and refrigerate dough balls, then add swirls and bake the next day. Bring chilled dough straight to the oven.

Q: How long do these keep in the fridge?
A: Stored airtight, they keep 4–5 days in the refrigerator.

Q: Why didn’t the swirl stay distinct?
A: Swirl was likely too thin, or dough too warm. Thicken the swirl with an extra tablespoon flour or chill the swirl before assembly.

Q: Can I freeze assembled cookies before baking?
A: Yes. Freeze assembled cookies on a sheet until solid, then transfer to a bag. Bake from frozen, adding 2–3 minutes to bake time.

Conclusion

For a slightly different take on peanut butter and brownie ribbons, see this tested version at Sugared & Stirred’s Peanut Butter Swirl Brownie Cookies, and for a filled brownie-cookie hybrid, try Sally’s Peanut Butter Filled Brownie Cookies. Enjoy experimenting with swirls and textures, and save a batch for friends.