Reese's S'mores Bars

Reese's Peanut Butter Cup S'mores bars are the perfect summertime treat. A delicious graham cracker cookie bar is stuffed with a layer of peanut butter cups and a layer of marshmallow fluff. These s'mores blondies are loved by all. Step-by-step photos teach you how to bake this delicious Reese's s'mores bar recipe! 

Some of my favorite memories growing up were walking to the local 7-Eleven with my best friend to get a bottle of Sprite and a King Size pack of Reese's Peanut Butter Cups. We did this as often as we could. I LOVE Reese's!

So after I made the classic s'mores bars I knew I would love swapping out regular chocolate for Reese's peanut butter cup!

I cannot tell you how many people love this, the combination of peanut butter, chocolate, marshmallow, and graham crackers is unreal!

Let's get to the recipe.

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• Ingredients
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Ingredients

You'll need:

• Unsalted Butter. Since we are creaming the butter and sugars you'll need your butter to be softened to room temperature.
• Sugars. I like to use a blend of white and brown sugar for the perfect flavor and texture. As brown sugar holds more moisture than white granulated sugar.
• Large Egg. In order for your egg to fully incorporate into the butter-sugar mixture it needs to be at room temperature. You can do this quickly by placing the egg in a bowl of warm water for 5 minutes before using it.  
• Pure Vanilla Extract. Most cookie doughs always benefit from the flavor of vanilla. I use the real stuff, no imitation for me!
• All-Purpose Flour. Adding too much or too little flour can alter the texture of the cookie drastically so I highly suggest weighing your flour versus using cups.
• Graham Cracker Crumbs. You can buy store-bought graham cracker crumbs or you can do it yourself just make sure to finely crush them. I find a food processor works best but you can also place them in a plastic bag and use a rolling pin to break them down.
• Baking Powder. This chemical leavening agent will give the cookie dough part just a little lift!
• Salt. Don't skip this ingredient, salt helps enhance all of the other ingredients' flavor profiles.
• Reese's Peanut Butter Cups. The star of the show, I like to use the snack size Reese's but you could use mini, you'll just need more!
• Marshmallow Fluff. Not to be confused with melting marshmallows this is a container of Marshmallow fluff or creme.

Next time try my brown butter gooey cake bars for another delicious bar recipe!

Baking is a science and to really achieve the best results I highly recommend investing in a kitchen scale. This OXO Kitchen Scale is the one I use and is also the number one recommended kitchen scale by Cook's Illustrated. Think about it -what one person scoops into a "cup" is completely different from what someone else scoops!

Instructions

Start by preheating the oven to 350°F/180C. Line an 8-inch square baking pan with foil so it overhangs on the side (this will help you pull them out after baking) lightly grease the foil with non-stick spray then set the pan aside. 

In the bowl of an electric mixer fitted with a paddle attachment or a large bowl with a handheld electric mixer cream together butter and sugar until light and fluffy. Make sure to scrape down the bowl to ensure everything is evenly combined.

Next, beat in the egg and vanilla extract.

Again, make sure you scrape the bowl down, you want no trace of egg left behind.

In a small bowl, whisk together flour, graham cracker crumbs, baking powder, and salt.

Add the dry mixture into the wet ingredients and mix at a low speed until combined, don't over mix!

Divide the dough in half and press half of the dough into an even layer on the bottom of the prepared pan. Place the peanut butter cups on top of the dough. You just want to get it to fit in a single layer, so I break the last three in half to fit down the sides.

Spread the marshmallow creme or fluff on top of the peanut butter cups. I like to use an ice cream scoop to sort of have the marshmallow already spread out then I find an angled spatula works best to get it into an even layer covering everything.

Place the remaining dough in a single layer on top of the fluff. I find the easiest way is to take a ball of dough and smash it between your hands to kind of make a flatter piece then lay each piece on top to fully cover the marshmallow.  

Bake for 30 to 35 minutes, until lightly browned. Cool the bars completely on a wire rack before cutting them into bars.

Store any leftovers in an air-tight container for up to 5 days.

Check out my s'mores cookies, how to make s'mores in the oven, s'mores dip, s'mores treats, or my s'mores brownies next!

More peanut butter cup recipes

If you like this recipe then you must love pb cups so you gotta try my peanut butter cup brownie recipe!

My no-bake peanut butter pie is topped with chopped peanut butter cups! Another great summer dessert!

My friend Karen makes the absolute best Pretzel Peanut Butter Cup Cookies!

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★★★★★ Please let me know if you make this recipe by leaving a star rating and comment below!

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This post was originally published on June 12, 2012, as of August 11, 2021, the post has been updated.