Marshmallow Peanut Butter Brownies

Disclaimer: This is not my recipe all the credit goes to Sarah Kieffer the recipe is from her 100 Cookies cookbook linked: here

Who loves chocolate and peanut butter? If you answered, “I absolutely do!” This Marshmallow Peanut Butter Brownies recipe is for you. I love the s’mores combination around the summertime, it reminds me of campfires and lake life. These are a big crowd pleaser and easy to make. You need to make these or you’re missing out on a go to summer time dessert.


Makes: 12 large or 24 small pieces

Disclaimer: This is not my recipe all the credit goes to Sarah Kieffer the recipe is from her 100 Cookies cookbook linked: here


  • Brownie Base
    • 1 cup plus 2 tbsp (160g) all-purpose flour
    • ¾ tsp salt
    • ½ tsp baking powder
    • 4 large eggs at room temperature
    • 1 ½ cups (300g) granulated sugar
    • ½ cup (100g) packed brown sugar
    • ½ cup (112g) canola oil
    • 2 tsp pure vanilla extract
    • 8 tbsp (1 stick or 113g) unsalted butter
    • 8 oz (226g) bittersweet chocolate chopped
    • ¼ cup (25g) Dutch-process cocoa powder
  • Marshmallow Peanut Butter Topping
    • ½ cup (107g) creamy peanut butter
    • ¼ cup (30g) confectioners’ sugar
    • 2 tbsp (29g) unsalted butter, at room temperature
    • ¾ tsp pure vanilla extract
    • Pinch of salt
    • ½ cup (70g) store-bought marshmallow fluff


  1. Adjust an oven rack to the middle of the oven. Preheat the oven to 350°F (180°C). Grease a 9x13in (23x33cm) baking pan and line with a parchment sling.
  2. In a small bowl, whisk together the flour, salt, and baking powder.
  3. In a large bowl, whisk together the eggs, granulated and brown sugars, canola oil, and vanilla.
  4. Place the butter and chocolate in a small, heavy-bottom saucepan set over low heat and melt together, stirring frequently to prevent the chocolate from scorching. Continue cooking until the mixture is smooth. Off the heat, add the cocoa powder to the chocolate and whisk until completely combined. Set aside
  5. In a medium bowl, mix together the peanut butter, sugar, butter, vanilla and salt until combined and completely smooth. Set aside.
  6. Add the chocolate mixture to the sugar-egg mixture and whisk until smooth. Add the flour mixture and stir with a spatula until just combined.
  7. Pour the brownie batter into the prepared pan. Dollop the peanut butter filling and the marshmallow cream over the top, alternating the two. Drag the tip of a butter knife through the batter, creating swirls.
  8. Bake until the sides of the brownies have set, the top is starting to crackle and look glossy, and a wooden skewer or toothpick inserted into the center comes out with crumbs, 26 to 32 minutes. The batter on the toothpick should not be wet but should have a good amount of crumbs, clinging to it.
  9. Transfer the pan to a wire rack and let cool completely. Use the parchment sling to gently lift the brownies from the pan. Cut them into bars and serve. Store brownies in an airtight container at room temperature for up to 2 days.

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