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Monster Mash Brookie at Insomnia Cookies: Brownie, Cookie, Snickers, Twix and M&M's in One Halloween Treat

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17 Oct 2026 • 5 min read

Monster Mash Brookie from Insomnia Cookies featuring a fudgy brownie, brown sugar cookie dough, Snickers, Twix and M&M's Halloween candy.

FOOD & FLAVOR NEWS | OCTOBER 17, 2026

Insomnia Cookies has a new Halloween dessert, and it doesn't hold back. The Monster Mash Brookie stacks a fudgy brownie and brown sugar cookie dough, then loads it up with three Mars candies: Snickers, Twix and M&M's. It's part of a limited-time Halloween collaboration between Insomnia Cookies and Mars.

The brookie got a fresh round of attention this week after Allrecipes covered it on October 17, 2026, with a tasting review and a look at how excited fans have been on social media.

You can get the Monster Mash Brookie nationwide through November 1, 2026, while supplies last. It shares the menu with two other Halloween cookies, Betwixed and Snick-or-Treat.

For snack lovers, it's an over-the-top seasonal treat built from candy they already love. For flavorists and bakery pros, it's a good look at how layering, texture and familiar ingredients can add up to something that feels new.

What Is the Monster Mash Brookie?

The Monster Mash Brookie is a brownie-cookie hybrid: a brownie base topped with brown sugar cookie dough and packed with pieces of Snickers, Twix and M&M's.

Bake Magazine reported on October 13 that it's one of three new Halloween items from the Insomnia Cookies and Mars partnership.

Here's what goes into it:

Fudgy brownie: A dense, moist chocolate base.
Brown sugar cookie dough: A soft, buttery layer with caramelized sugar notes.
Snickers: Chocolate, caramel, peanuts and nougat.
Twix: Chocolate-coated cookie and caramel.
M&M's: Candy-coated milk chocolate.

The idea is to get a few different textures and flavors in every bite.

Why Everyone's Talking About It

Insomnia Cookies started promoting its candy collection in early October, and trade publications picked up the Mars collaboration on October 13.

The latest wave of interest came from Allrecipes' October 17 piece, which put the lineup in front of a much bigger audience and included a firsthand taste test. The article also rounded up social media reactions, and fans were clearly eager to try the candy-stuffed cookies.

It's not hard to see the appeal. The brookie mixes classic Halloween candy with the brownie-cookie hybrid trend that's been popping up at bakeries everywhere.

What Does It Taste Like?

Think chocolate, caramel, brown sugar, peanuts and buttery baked goodness.

The brownie leads with rich, dense chocolate. The cookie layer brings buttery sweetness and a more classic cookie feel. The candy pieces fill in the rest.

Chocolate and Brownie

The brownie base gives you deep cocoa flavor and a fudgy bite. Snickers, Twix and M&M's add milk chocolate on top of that, so you're getting several kinds of chocolate in one dessert.

Brown Sugar and Caramel

The brown sugar cookie dough adds warm, slightly toasty sweetness. Caramel from the Snickers and Twix doubles down on those notes and runs through the whole thing.

Peanut and Nougat

Snickers brings roasted peanuts, a little salt and chewy nougat, which help cut through all the sweet chocolate and cookie.

Crunch

Twix adds cookie crunch and M&M's add that snappy candy shell. Without them, the brownie and cookie layers could start to feel a bit one-note.

Bite by bite, it goes something like this: rich chocolate, then buttery brown sugar cookie, then caramel, roasted peanut and a crunchy candy finish.

Early Reviews

So far, so good.

Allrecipes tried both the Monster Mash Brookie and the Snick-or-Treat cookie. Their reviewer liked the layered build of the brookie and said keeping the brownie and cookie separate helped spread the flavors out evenly.

It also wasn't as sugary as you might expect from a dessert with three candy bars in it. That's no small thing, since piling on candy inclusions can easily make a baked good cloyingly sweet.

The reviewer did say the M&M's alone might have been enough candy. Loaded desserts like this tend to split opinions, so your mileage may vary.

Read the full Allrecipes review.

Two More Halloween Cookies

The brookie has company. The 2026 Insomnia Cookies and Mars lineup includes two more limited-edition cookies.

Betwixed

Betwixed is a vanilla sugar cookie filled with caramel and topped with chopped Twix. It's all about buttery vanilla, caramel and milk chocolate, with the Twix adding crunch. If the brookie feels like a lot, this is the simpler pick built around the classic Twix combo.

Snick-or-Treat

Snick-or-Treat starts with a dark chocolate cookie and packs in chewy caramel bits, milk chocolate chunks and Snickers pieces. Expect a deeper chocolate flavor with caramel, peanut and nougat in the mix.

Snack Food & Wholesale Bakery confirms all three are part of the same limited-time Halloween collection.

What Flavorists Can Take From the Monster Mash Brookie

For flavor professionals, the brookie is a nice example of layered flavor design. Insomnia didn't invent a new flavor. It combined well-known dessert and candy profiles into a different eating experience.

1. Familiar flavors, new format

Chocolate, caramel, peanuts and cookie are nothing new. Put them together in a brownie-cookie hybrid, though, and the experience is different from eating any of those candies on their own. Sometimes innovation is about the format, not the flavor.

2. Texture shapes flavor

Texture does a lot of the work here. The brownie is dense and moist, the cookie is soft, and the candy adds crunch and chew. Those contrasts affect how long flavors linger and how rich the whole thing feels.

3. A little salt goes a long way

Peanuts and caramel can bring subtle saltiness that helps balance the sweet brownie and cookie layers.

4. Known brands lower the risk

Everyone knows what Snickers, Twix and M&M's taste like. Combining them gives Insomnia something that feels new without asking customers to take a chance on an unfamiliar flavor. That's a smart move for a limited-time bakery item.

Why Halloween Works So Well for Candy Desserts

Halloween is basically built on chocolate and candy, and the brookie leans right into that. The name has a playful monster theme, and the three-candy mix feels like dumping out your trick-or-treat bag.

It's also made for social media. Bright candy pieces and visible brownie and cookie layers look great in photos, especially when the brookie gets broken in half. For bakery chains, products like this create seasonal buzz without having to invent a whole new category.

When Can You Get It?

The Monster Mash Brookie and the rest of the Halloween collection are available at participating Insomnia Cookies locations nationwide through Sunday, November 1, 2026, while supplies last.

Check the Insomnia Cookies website for ordering options near you, since availability can vary by store. This is a limited-time Halloween item, so don't count on it sticking around.

Is It Worth Trying?

If you like brownies, chocolate chip cookies and Mars candy, this is pretty much made for you. The big draw is getting several desserts in one.

If you prefer simpler sweets, it might be a bit much. Fans of chocolate, caramel and peanut will probably love the variety. Either way, the contrast between the dense brownie, the brown sugar cookie and the crunchy candy is the main reason to give it a shot.

The Bottom Line

The Monster Mash Brookie is one of the more memorable Halloween bakery launches this October. Made with Mars, it packs a fudgy brownie, brown sugar cookie dough, Snickers, Twix and M&M's into one layered chocolate-and-caramel treat.

The October 17 coverage has put it back in the spotlight, and with a November 1 end date, there isn't much time left to try it.

For flavorists, it's proof that familiar candy flavors still have plenty of room to grow when you play with texture and format. For everyone else, it's simple: a brownie, a cookie and three Halloween candy favorites rolled into one.

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