These Marshmallow Peanut Butter Brownies should be your next decadent go-to treat! They combine rich and chewy, chocolatey brownies with marshmallow fluff and a peanut butter filling swirled all over the top! They are a fantastic recipe from my friend Sarah Kieffer's new cookbook, 100 Cookies that are perfect for any brownie lover in your life!
In a medium bowl, mix together the peanut butter, powdered sugar, unsalted butter, vanilla, and salt until combined and completely smooth. Set to the side.
½ cup Creamy Peanut Butter, ¼ cup Powdered Sugar, 2 tablespoon Unsalted Butter, Pinch of Salt
brownies
Adjust an oven rack to the middle of the oven. Preheat the oven to 350ºF (180ºC). Grease a 9 by 13 inch (23 by 33 cm) baking pan and line with a parchment sling.
In a small bowl, whisk together the flour, salt, and baking powder.
1 cup + 2 tablespoon All-Purpose Flour, ¾ teaspoon Salt, ½ teaspoon Baking Powder
In a small bowl, whisk together the eggs, granulated and brown sugars, canola oil, and vanilla.
4 Large Eggs, 1 ½ cups Granulated Sugar, ½ cup Brown Sugar, ½ cup Canola Oil, 2 teaspoon Pure Vanilla Extract
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.
8 tablespoon Unsalted Butter, 8 oz Bittersweet Chocolate, ¼ cup Dutch Process Cocoa Powder
Add the chocolate mixture to the sugar-egg mixture and whisk until smooth. Add the flour mixture and stir until just combined.
assembling the marshmallow peanut butter brownies
Pour the brownie batter into the prepared pan. Dollop the peanut butter filling and the marshmallow creme over the top, alternating the two. Drag the tip of a butter knife through the batter, creating swirls.
½ cup Store-Bought Marshmallow Fluff
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.
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.
Use the parchment sling. This is helpful when removing the brownies from the pan to cool and makes it easier to cut them as well!
Warm the Marshmallow Fluff. I found that heating the marshmallow fluff in the microwave for 15 seconds helped with dolloping it onto the top of the brownies.
Chocolate and Butter Alternative Microwave Melting Method. Heat for 45 - 60 seconds at medium power. Stir, then repeat until both ingredients have fully melted and are smooth. Add in the cocoa powder after.
Mix up the peanut butter filling first. This is just a little bit of a time saver tip. Once you pour the brownie batter into the pan, you'll want to dollop on the peanut butter filling and marshmallow fluff immediately after.