last updated on October 29, 2026
Welcome to part one of my new series, Cereal Cookies! We are starting off strong with these rice krispie treat cookies, that are definitely not your average cookie. It’s a brown butter cookie with rice krispie brittle and marshmallow fluff. It tastes like the best rice krispie treat you’ve ever had and I think you’ll be obsessed.
Rice krispie brittle was something I had never seen or heard of, but when I was thinking of this cookie I wanted a way for the rice krispies to stay CRISPY. I wanted that crunch factor, so I figured what better way than to put them into a crunchy, crispy brittle. And the result is incredible. It is kind has the taste of a sea foam candy, but with the delicate crunch of rice krispies. And paired with the marshmallows? Sheesh this is a cookie you won’t forget.
ingredients needed
rice krispie cookies
- 1/2 cup butter
- 1 ice cube
- 1/2 cup brown sugar
- 1/4 cup granulated sugar
- 1 egg
- 1 tsp vanilla extract
- 1 1/4 cup flour (165 grams)
- 1/2 tsp baking soda
- 1/2 tsp salt
- 1/2 cup marshmallow fluff
rice krispie brittle
- 3/4 cup sugar
- 3 tbsp water
- 3 tbsp butter
- 1 1/2 cups rice krispies
- 1/2 tsp baking soda
- 1/2 tsp salt
other recipes you will love
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- date, cheddar, and dark chocolate cookies
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- cinnamon oatmeal cookies
rice krispie treat cookies
[PREP] 45 minutes
[COOK] 15 minutes
[TOTAL] 1 hour
Ingredients
rice krispie brittle
- 3/4 cup sugar
- 3 tbsp water
- 3 tbsp butter
- 1 1/2 cups rice krispies
- 1/2 tsp baking soda
- 1/2 tsp salt
rice krispie cookies
- 1/2 cup butter
- 1 ice cube
- 1/2 cup brown sugar
- 1/4 cup granulated sugar
- 1 egg room temp
- 1 tsp vanilla extract
- 1 1/4 cup flour 165 grams
- 1/2 tsp baking soda
- 1/2 tsp salt
- 1/2 cup marshmallow fluff
Instructions
- Begin by making the rice krispie brittle. Prep a baking sheet lined with parchment paper and set aside. Add the sugar, water, and butter to a medium sized pot over medium heat. Stir continually while the butter starts the melt. When the mixture starts to bubble, stop actively stirring.
- Let the mixture continue to cook, swirling the pot every minute to gently stir. After 5-6 minutes the sugar will start to change color. When it becomes a light brown color, turn off the heat. Add the rice krispies, while actively stirring. Once all the rice krispies are well-coated, add the baking soda and salt, and stir quickly. Once everything is well combined, carefully transfer the mixture to the lined baking sheet. Use a spoon to spread the brittle into a thin layer and set aside to cool completely.
- Now begin making the cookies. Start by browning the butter. Cut the butter into cubes and add it to a pan over medium heat. Stir as the butter starts to melt. Continue stirring while the butter begins to bubble. After 3-5 minutes, the butter will start to foam up, then the foam subsides. After the foam subsides, you'll be left with brown, nutty smelling butter. Carefully pour the brown butter into a separate container. Add the ice cube and stir until it's melted. Transfer to the freezer for 10 minutes to cool.
- Add the slightly cooled brown butter to a stand mixer (you can also use a hand mixer). Add the brown sugar and granulated sugar. Mix for 2-3 minutes until the butter and sugars are fully combined.
- Add the egg and vanilla extract and mix until combined. Add the flour, baking soda, and salt. Mix until just combined.
- Preheat the oven to 350F.
- By now the rice krispie brittle should be cooled. Use a rolling pin or a spoon to break up the brittle into smaller pieces. Add a handful of the brittle (a heaping 1/2 cup) and mix until just combined.
- Use two spoons to carefully spread dollops of marshmallow fluff across the top of the dough. Use a large cookie scoop (1/4 cup) to scoop out the dough, making sure to get some marshmallow fluff in each scoop.
- Place up to 4 dough balls on a parchment lined baking sheet. Press an extra piece of rice krispie brittle on top of each dough ball. Transfer to the oven and bake for 7-9 minutes, until the cookies are just set.
- Because of the marshmallow fluff, the cookies will likely come out irregularly shaped. Use a round cookie cutter or bowl to swirl around the cookies, bringing all those rough edges in. Let the cookies cool on the baking sheet for 5 minutes, then transfer to a cooling rack to cool completely. Enjoy!
Something happened to my brittle. It doesn’t look like yours. It got all weird and grainy and nothing stuck together after I put the salt and baking soda in.
hi! i’m so sorry the brittle didn’t work. did the brittle turn a darker amber color?
Try cooking the butter/water/sugar mixture a little longer before adding in the krispies & baking soda/salt. I did the same thing my first try ….. I thought as soon as it changed from a clear color I was to add in the other ingredients & I was going to overcook/burn the sauce. Just keep going though …. The big bubbles will subside & and look for the color in th picture. My stove time took longer than 5-6 min to acheive this. It was more like 8-9 min! Hope this helps
The same exact thing happened to me 🙁 Mine started to get grainy as soon as I added the rice crispies (then got more grainy when I added the baking soda/salt). It was almost like there wasn’t enough fluid? Wondering if I overcooked the butter/sugar/water mixture and too much fluid cooked off before I added the crispies?
hi! yes, it sounds like the mixture was cooked too much. if you have a candy thermometer, it should reach around 300F when you add the rice krispies. i hope this helps! let me know if you have any other questions.
The cereal is too much weighing it by cup. You only need 40.5g. Mine did the same thing the first time.
Like always- the best cookies EVER!!! They looked super spread out in the oven but I trusted the process and reshaped them when they came out.
YAY i’m so glad you loved these!!!! and yes the marshmallow fluff can make these spread wacky but luckily reshaping does the trick
what do you think about doing these…. but with golden grahams?:)
As always thank you!
hi! that should work! the brittle will hold anything together, and i can’t see why there would be a problem with using a different kind of cereal if that’s what you prefer!
Hi 🙂
Looking forward to trying these cookies.
Was wondering if you’ve ever added chocolate chips?
Thanks!
Ande
hi! you can totally include chocolate chips here. i didn’t include them because i think there are already enough flavors, but they will work fine if you want to throw some in!
I seriously loved these cookies! The recipe was easy to follow. The brittle added lovely texture to the cookie. I also had left over brittle to snack on so that was a bonus! I’d honestly eat the brittle solo because it was that good. Completely obsessed with this recipe and will be using it again in the future.
YAY so glad you enjoyed these!! and i am totally with you on snacking on the brittle on it’s own!
Great cookies! The brittle held up so well and the tastes and textures were divine together. The great thing was I had so much extra brittle that I can make another batch!
yay so glad you loved these!!
Hello, and thank you for the recipe. I plan on doing the brittle, but can I leave out the baking soda since I’m allergic to it? Will the texture change if it’s not added to it?
hi! if you leave out the baking soda, the mixture will be more like a toffee instead of a brittle. it should still work out fine, but won’t have the airy texture the brittle will!
Terrible recipe ..don’t waste your time! Need brown sugar to carmalize more of it to stick ingredients together.
hi! i’m sorry this didn’t work out for you. can you elaborate?
Do you think I could make the dough then freeze it into balls for later use?
yes, totally! just store them in an airtight container and they should stay good for 3-4 months in the freezer.
Could you possibly stuff the dough with a big marshmallow instead of using fluff OR turn some marshmallows into fluff for it? Would it turn out different if you do?
yes! you can use marshmallows. if using the regular size, i would cut them in half, then put half of a marshmallow on top of each dough ball. it won’t melt into the cookie quite as well as the fluff does, but will work totally fine!
Hi! I’d like to make these. Would I be able to make the dough a couple days in advance and refrigerate until ready to bake ? Would the brittle get soft in the refrigerator ?
hi! i haven’t tried putting them in the fridge for multiple days, but i fear it would mess with the texture of the brittle. i would recommend not adding the brittle initially, then adding a large chunk on top of each dough ball right before baking!
Would it be ok to use regular mini marshmallows rather than fluff? Would it just be a 1/2 cup of marshmallows instead of fluff if so?
yes, that is fine! they won’t spread into the cookie as much, but they will work fine!
These worked PERFECTLY and tasted delcious!
Thanks so much for the recipe 🙂
so glad you loved these!!
What is the purpose of the ice cube? Also wondering if I can make this with 1 full stick melted butter instead of browning it?
the ice cube adds back water that evaporates off when you brown the butter! if you don’t want to brown the butter you can absolutely just use a normal stick of butter, using the full stick.
Hi Mallory, I tried to bake a few of these cookies last night. I followed the dough making directions closely and had my oven at 350, but even after 11 minutes of baking my cookies still weren’t baked through. Do you have any ideas of what I may have done or could change?
hi! i would try upping the bake time. depending on how hot or cold your oven runs you may need to adjust. they may take closer to 14 minutes.