Mississippi Mud Cookies (Brownie Mix Shortcut)
These Mississippi mud cookies take the classic Southern potluck cake and turn it into a big, rich, fudgy cookie topped with toasted marshmallows, pecans, and a drizzle of homemade chocolate icing. One easy shortcut with a box of brownie mix, and the rest is homemade. If you are a chocolate lover, this cookie is for you.
- One easy shortcut: the dough starts with a box of brownie mix, plus just eggs and oil
- All the Mississippi mud flavors: chocolate, marshmallow, pecans, and chocolate icing
- Nut-free friendly: add the pecans on top so you can leave some cookies plain
- Big and decadent: the best of brownies and cookies in one bite
- Great for gifting: box them up for neighbors, teachers, or holiday trays
From the Potluck Table to the Cookie Jar
If you’ve ever been to a potluck in the South, you know there’s always a Mississippi mud cake sitting on the dessert table. It’s one of those desserts everybody knows and loves. So I thought, why not take that cake and turn it into a cookie?
If you’ve watched some of my other videos, you know I am a chocolate lover, so this recipe is right up my alley. We take one little shortcut by starting with a brownie mix, and then we do some homemade things too: the marshmallows, the pecans, and a chocolate icing you drizzle right over the top.
When we did the taste test, I told Darren I don’t know what we could do to improve on this cookie. Now, he is not a chocolate person, so he had some opinions. But there are a whole lot of us chocolate lovers out there, and if you’re one of them, you’re going to love this.
Mississippi Mud Cookies
Makes about 16 large cookies. Prep 20 minutes, chill 20 minutes, bake about 12 minutes, then cool about 30 minutes before icing.
Ingredients
For the cookies:
- 1 box (about 18 oz) brownie mix (plain, not the kind with a fudge packet)
- 2 large eggs
- ¼ cup vegetable oil
- 1 cup semisweet mini chocolate chips
- ½ cup rough chopped pecans (optional)
- About 1½ cups mini marshmallows
For the chocolate icing:
- ½ cup (8 tablespoons) butter, softened
- 3 cups powdered sugar
- 4 heaping tablespoons cocoa powder
- 1 teaspoon vanilla extract
- About 6 tablespoons milk
Instructions
- Make the dough. Add the brownie mix to a large bowl, then add the oil and the eggs one at a time. Stir it together with a scraper or a wooden spoon. There’s not as much liquid as you’d use for brownies, so it takes a few extra stirs, but it comes together pretty quickly. Check underneath for any dry pockets.
- Add the chocolate chips. Stir in the mini chocolate chips until they’re throughout. If you want pecans in every cookie, stir them in now too. The dough will be a little bit thick.
- Scoop, then chill. The dough needs to chill for 20 minutes, but here’s my little tip: scoop your cookies first, then put the whole tray in the fridge. It’s so much easier to scoop now than once the dough is chilled. Use generous, overflowing scoops and don’t flatten them, and leave room between them because they will spread.
- Preheat the oven. While the cookies chill, preheat your oven to 350°F.
- Bake. Bake for 10 to 12 minutes. I pulled mine at 11 minutes. They’ll still be a little soft in the center, and that’s exactly what you want.
- Add the marshmallows. Place a few marshmallows on top of each cookie and poke them down just a little bit. If you love marshmallows, go crazy and cover the whole cookie.
- Add the pecans on top (optional). If you didn’t put pecans in the dough, sprinkle a few between the marshmallows now. This way you control which cookies get nuts and can leave some plain for anyone who doesn’t care for them or has an allergy. Just be careful the pecan cookies don’t touch the nut-free ones.
- Back in the oven for 1 minute. You want the marshmallows to puff and just start to turn a touch brown, but still look like marshmallows. The cookies will keep cooking after they come out of the oven. Let them cool completely.
- Make the icing. Microwave the softened butter for about 8 to 10 seconds, just until it’s barely starting to melt. Add the powdered sugar, cocoa, vanilla, and about half the milk. Whisk, then add more milk a tablespoon at a time until the icing is smooth. If it’s still stiff, pop it back in the microwave for 10 to 12 seconds and whisk again until it’s pourable.
- Drizzle and set. Spoon the icing over each cookie in a random drizzle so some marshmallows still peek out. Let the icing set up a bit before serving.
Tips for the Best Mississippi Mud Cookies
- Use a plain brownie mix. Skip the boxes that come with a separate fudge or syrup packet. A standard 18-ounce box works best.
- Scoop before chilling. Cold brownie dough is hard to scoop, so get them on the tray first.
- Don’t overbake. The centers should still look soft when you pull them out. They’ll set up as they cool.
- Only one minute for the marshmallows. Any longer and they’ll melt flat instead of keeping their shape.
- Make the full batch of icing. I only made a half batch in my little pitcher and it covered just 8 cookies. The amounts above are the full batch for all of them.
- Thin the icing for a lighter drizzle. Warm it a little longer so it runs in thin streams and goes farther.
- Make them a little smaller if you like. This is a rich cookie, and most people will only eat one.
Frequently Asked Questions
What are Mississippi mud cookies?
They’re a cookie version of the classic Southern Mississippi mud cake: a fudgy chocolate cookie topped with marshmallows, pecans, and chocolate icing.
Can I use any brownie mix?
Yes, any brand works. Just use a plain mix, about 18 ounces, without a separate fudge packet.
Why do I need to chill the dough?
Chilling helps the cookies hold their shape so they don’t spread too thin in the oven.
Can I make these without nuts?
Absolutely. The pecans are optional. Add them on top after baking so you can leave some cookies nut-free, or skip them entirely.
Can I use regular chocolate chips instead of mini?
Yes. Mini chips spread more evenly through the dough, but regular semisweet chips work fine.
How do I keep the marshmallows from melting flat?
Only return the cookies to the oven for about one minute. You want them puffed and just barely golden.
Can I spread the icing instead of drizzling it?
Yes. Spreading gives you a more traditional Mississippi mud look. I like the drizzle so some marshmallows peek through.
How do I store Mississippi mud cookies?
Once the icing is set, store them in a single layer (or with parchment between layers) in an airtight container at room temperature for up to 3 days.
Can I freeze these cookies?
Yes. Freeze the iced, fully set cookies in a single layer, then transfer to a freezer container. Thaw at room temperature.
Are these good for gifting?
They make wonderful gifts. Box them up in some cute little boxes for neighbors, teachers, or holiday cookie trays. Nobody is going to be mad about that.
One More Chocolate Recipe
If you’re one of those chocolate lovers out there, be sure to try my Chocolate Chip Cookie Cobbler. You pour boiling water right over the cookie dough, and it’s so yummy too.
I hope you’ll give these Mississippi mud cookies a try. I think your family and friends will love them.
And remember to go out today and find somebody who needs a little bit of kindness and give them some of yours.
With love,
Mary Katherine
Mississippi Mud Cookies
Ingredients
Cookies
- 1 box brownie mix about 18 oz, plain (not the kind with a fudge packet)
- 2 large eggs
- 1/4 cup vegetable oil
- 1 cup semisweet mini chocolate chips
- 1/2 cup pecans rough chopped, optional
- 1 1/2 cups mini marshmallows
Chocolate Icing
- 1/2 cup butter softened (8 tablespoons)
- 3 cups powdered sugar
- 4 tablespoons cocoa powder heaping
- 1 teaspoon vanilla extract
- 6 tablespoons milk add a little at a time, as needed
Instructions
Cookies
- In a large bowl, add the brownie mix, oil, and eggs (one at a time). Stir with a scraper or wooden spoon until no dry pockets remain. The dough will be thick.
- Stir in the mini chocolate chips. If you want pecans inside every cookie, stir them in now.
- Scoop generous, overflowing balls of dough onto a lined baking sheet, leaving room to spread. Do not flatten.
- Chill the tray in the refrigerator for 20 minutes. Meanwhile, preheat the oven to 350°F.
- Bake 10 to 12 minutes, until the edges are set and the centers are still slightly soft.
- Press a few marshmallows onto each cookie. Sprinkle pecans between the marshmallows on any cookies you want with nuts.
- Return to the oven for 1 minute, just until the marshmallows puff and barely start to brown. Cool completely.
Chocolate Icing
- Microwave the softened butter 8 to 10 seconds, just until it barely begins to melt.
- Add the powdered sugar, cocoa powder, vanilla, and half the milk. Whisk, adding more milk 1 tablespoon at a time until smooth.
- If the icing is too thick to drizzle, microwave 10 to 12 seconds and whisk again until pourable.
- Drizzle the icing over the cooled cookies with a spoon. Let it set before serving.
Notes
- Brownie mix: Use a plain 18 oz brownie mix. Skip mixes that include a separate fudge packet.
- Scoop first: Scoop the dough before chilling. It is much harder to scoop once cold.
- Nut-free option: Add pecans on top after baking so you can leave some cookies plain. Keep the pecan cookies separate from the nut-free ones.
- Full batch of icing: These icing amounts are a full batch. A half batch covers only about 8 cookies.
- Thinner drizzle: Warm the icing a few seconds longer so it runs in thin streams and goes farther.
- Size: These are rich. Make them smaller if you like and reduce the bake time slightly.
- Storage: Store in an airtight container at room temperature up to 3 days, or freeze once the icing is set.
