Toasted Marshmallow Okay-Bars. – Half Baked Harvest

Toasted Marshmallow Special K-Bars – a sweet, salty, peanutty, and just slightly toasty chocolate treat that’s impossible not to love. These bars are made with creamy peanut butter, salted butter, toasted marshmallows, and topped with rich chocolate. They’re chewy, gooey, a little nostalgic, and totally addictive. Whether you’re making them for a summer dessert, school bake sale, or just because—it’s a guaranteed crowd-pleaser.

Oh, how I adore this recipe! My mom is known for a handful of classic desserts—her oatmeal chocolate chip cookies, death by chocolate cake, and of course, her famous Special K-Bars. I don’t know if K-Bars are a strictly Midwest thing, or where the original recipe even came from, but growing up, no one made them quite like my mom. She just had that magic touch.

Her recipe was simple and very old-school: 1 cup creamy peanut butter, 1 cup Karo syrup, and 1 cup sugar, melted together and mixed with cornflakes. She’d press it into a pan, melt a good amount of semi-sweet chocolate chips for the topping, and that was it. Classic. And so good! Any time she made them, they disappeared within a day—everyone loved them.

Today, I’m giving her classic bars a little twist by adding toasted marshmallows. Think of it as a mash-up between a marshmallow treat and a K-bar—chewy, chocolatey, and just a little gooey in the best way. They’re fun to make (no matter your age!) and even more fun to eat.

Let’s dive into the details

Ingredients

• mini marshmallows
• salted butter
• creamy peanut butter
• cornflakes
• regular marshmallows
• semi-sweet chocolate chips

Special Tools

You’ll need to use your oven’s broiler for this recipe. You’ll also need a large pot, sheet pan, and a 9×13 pan.

Steps

Step 1: Make the Peanut Butter Mixture

In the largest pot you have, melt 1 ½ sticks of salted butter with creamy peanut butter over medium heat. Stir frequently and bring the mixture to a gentle boil—this should take about 5 minutes. The mixture should be smooth and fully combined.

If you like, add a pinch of flaky sea salt for a little extra flavor.

Step 2: Add Marshmallows and Cereal

Once the peanut butter mixture is smooth, stir in the mini marshmallows until completely melted and gooey.

Then, mix in the cornflake cereal. Stir until the cereal is well coated in the peanut butter-marshmallow mixture.

Step 3: Toast the Marshmallows

To get that toasted marshmallow flavor, arrange a layer of mini marshmallows on a baking sheet and broil until golden and lightly charred.

Important: Don’t walk away while these toast! Every broiler is different, and marshmallows can go from perfectly golden to burnt in seconds. Watch them closely.

Once toasted, gently fold the marshmallows into the cereal mixture. No need to overmix—swirls and pockets of toasted marshmallow are exactly what you want.

Step 4: Press and Top with Chocolate

Line a baking pan with parchment paper and press the cereal mixture firmly into the pan.

Melt the chocolate chips until smooth, then pour the melted chocolate over the bars and spread it out evenly.

Refrigerate the bars until set—about 2 hours. Once firm, cut them into squares or bars.

They’ll be a little gooey, a little messy, and totally irresistible. Perfect for backyard BBQs, picnics, or just a fun summer dessert!

Looking for easy party summer desserts? Here are a few ideas: 

Chewy Chocolate Peanut Butter Bars

Crinkle Top Brownies

Chocolate Peanut Butter Pretzel Blondies

Homemade Vegan Peanut Butter Twix Bars

Caramel Butter Cake with Fudgy Chocolate Frosting

Retro-Style Chocolate Sheet Cake

Lastly, if you make these Toasted Marshmallow K-Bars, be sure to leave a comment and/or give this recipe a rating! Above all, I love hearing from you and always do my best to respond to each and every comment. And, of course, if you make this recipe, don’t forget to tag me on Instagram! Looking through the photos of recipes you all have made is my favorite!