Ingredients
For the Cookie Dough
- 1 cup unsalted butter, softened
- 1 cup creamy peanut butter
- 1 cup granulated sugar
- 1 cup light brown sugar, packed
- 2 large eggs, at room temperature
- 1 teaspoon pure vanilla extract
- 1 1/2 cups all-purpose flour
- 1 1/2 cups graham cracker crumbs
- 1 teaspoon baking soda
- 1/2 teaspoon salt
For the Marshmallow-Chocolate Filling
- 1 cup mini marshmallows
- 1/2 cup (about 85 g) semi-sweet chocolate chips
- 1/4 cup (about 65 g) creamy peanut butter
Ingredients and Why They Matter
The cookie dough starts with unsalted butter and creamy peanut butter, which gives you a rich, flavorful base and that classic peanut butter cookie chew. Using both granulated sugar and light brown sugar adds sweetness plus moisture and a subtle caramel note from the molasses in the brown sugar, which helps keep the cookies soft in the center. Eggs bind the dough and contribute to structure and tenderness, while vanilla rounds out the flavor so the cookies taste like bakery peanut butter–graham cookies rather than just plain peanut butter.
All-purpose flour gives the cookies their structure, but the twist here is the graham cracker crumbs: they replace part of the flour and bring that unmistakable graham flavor that screams “s’mores” while also adding a slightly sandy, tender texture. Baking soda provides lift and helps create a soft, chewy interior with lightly golden edges. A bit of salt keeps the cookies from being overly sweet and enhances both the peanut butter and graham notes.
The filling is simple but smart. Semi‑sweet chocolate chips give you classic s’mores chocolate flavor and melt into a smooth base; semi‑sweet keeps the filling from tipping too sweet. Creamy peanut butter stirred into the melted chocolate creates a thicker, richer filling that clings to the cookies and reinforces the peanut butter theme. Mini marshmallows are folded in once the chocolate‑peanut butter mixture cools a bit; they soften and meld into the filling without fully dissolving, giving little pockets of marshmallow in every bite.
Step-by-Step Instructions
Step 1: Make the Cookie Dough
I preheat the oven to 350°F (175°C) and line a couple of baking sheets with parchment paper so the cookies release easily and bake evenly.
In a large mixing bowl, I cream together the softened butter, 1 cup of creamy peanut butter, the granulated sugar, and the packed light brown sugar. Using an electric mixer on medium‑high speed, I beat this mixture for 2–3 minutes until it looks light, fluffy, and paler in color. This step dissolves some of the sugar and adds air, which helps the cookies bake up soft instead of dense.
Next, I add the eggs one at a time, beating well after each addition so the mixture stays smooth and emulsified, then mix in the vanilla extract. In a separate bowl, I whisk together the all‑purpose flour, graham cracker crumbs, baking soda, and salt until everything is evenly distributed. I gradually add the dry mixture to the wet ingredients, mixing on low just until the dough comes together and no dry pockets remain. Overmixing at this point can toughen the cookies, so as soon as the flour disappears, I stop.
Step 2: Scoop, Flatten, and Bake
Using a cookie scoop or tablespoon, I portion the dough into roughly 1‑inch balls, about 1 tablespoon of dough each. I place the dough balls on the prepared baking sheets, spacing them about 2 inches apart to allow for spreading. Then I gently flatten each ball with my palm or the bottom of a glass so they’re slightly disk‑shaped; this helps them bake into even rounds that are easier to sandwich later.
I bake the cookies for 10–12 minutes, just until the edges are lightly golden and the centers still look a bit soft and puffy. They’ll continue to set as they cool, so I avoid overbaking if I want that soft, chewy texture. Once they come out of the oven, I let them cool on the baking sheet for about 5 minutes to firm up, then transfer them to a wire rack to cool completely. The cookies need to be fully cool before filling or the filling will melt and run.
Step 3: Prepare the Filling and Assemble
While the cookies cool, I make the marshmallow‑chocolate filling. In a microwave‑safe bowl, I combine the semi‑sweet chocolate chips and 1/4 cup creamy peanut butter. I microwave in 20‑second bursts, stirring after each, until the chocolate is fully melted and the mixture is smooth and glossy. Then I let this mixture cool for 5–10 minutes; it should still be spreadable but not hot, so it doesn’t instantly melt the marshmallows or the cookies.
Once slightly thickened, I stir in the mini marshmallows until they’re evenly coated in the chocolate‑peanut butter mixture. Then I flip half of the cooled cookies upside down on a work surface—these will be the bottoms. I spoon about 1–2 teaspoons of filling onto the center of each bottom cookie, spreading it gently but not all the way to the edges to leave room for the filling to spread when pressed.
I top each one with a second cookie, right‑side up, and press gently to form a sandwich. The goal is to press just enough to bring the filling out toward the edges without squeezing it all out. Once assembled, I let the cookies sit for about 30 minutes at room temperature so the filling can firm up slightly, which makes them easier to stack, serve, and eat without too much mess.