Insomnia Cookies is adding a candy-filled dessert to its Halloween 2026 lineup with the Monster Mash Brookie, a limited-time treat created in collaboration with Mars. The new dessert combines a fudgy brownie base, brown sugar cookie dough and three popular candy brands: Snickers, Twix and M&M’s.
The Monster Mash Brookie is part of a three-item Halloween collection available at Insomnia Cookies locations across the United States through November 1, 2026, while supplies last. The seasonal lineup also includes the Betwixed cookie and the Snick-or-Treat cookie, giving customers several options inspired by classic Halloween candy.
What Is the Monster Mash Brookie?
The Monster Mash Brookie combines two familiar desserts in one treat. It features a brownie layer topped with brown sugar cookie dough and loaded with pieces of Snickers, Twix and M&M’s. The layered construction brings together the rich chocolate flavor of a brownie, the sweetness of cookie dough and the contrasting textures of the candy pieces.
The combination makes the dessert a notable addition to Insomnia Cookies’ seasonal menu, particularly for customers who enjoy chocolate-based baked goods and candy-inspired treats. Rather than featuring just one candy brand, the brookie brings together three Mars favorites in a single dessert.
Insomnia Cookies Adds Two More Halloween Treats
The Monster Mash Brookie is not the only new item in the company’s Halloween collection. Insomnia Cookies has also introduced Betwixed and Snick-or-Treat as part of its collaboration with Mars.
The Betwixed cookie starts with a vanilla sugar cookie filled with caramel and topped with chopped Twix pieces. The combination incorporates the flavors of a classic sugar cookie with caramel and chocolate-covered cookie candy.
The Snick-or-Treat cookie takes a different approach, featuring a dark chocolate base filled with chewy caramel bits, milk chocolate chunks and Snickers pieces. Its chocolate-forward profile distinguishes it from the vanilla-based Betwixed cookie and the brownie-and-cookie combination of the Monster Mash Brookie.
How Long Will the Monster Mash Brookie Be Available?
Insomnia Cookies’ Halloween collection is scheduled to remain available nationwide through Sunday, November 1, 2026, while supplies last. Because the items are part of a limited-time seasonal promotion, availability may vary by location and can change as individual stores sell through their inventory.
Customers interested in trying the Monster Mash Brookie can check the Insomnia Cookies website or app for current menu availability, local ordering options and pickup or delivery details. Prices may vary by location and ordering channel, so customers should confirm the price displayed for their selected store before placing an order.
What the Mars Collaboration Means for Halloween 2026
The collaboration brings familiar candy brands into Insomnia Cookies’ bakery menu during the Halloween season, when candy-inspired desserts are a natural fit for the holiday. By combining Snickers, Twix and M&M’s with cookies and brownies, the company is offering a different way for customers to enjoy recognizable confectionery flavors.
The Monster Mash Brookie stands out within the collection because it combines a brownie and cookie dough with all three candy brands. Betwixed focuses on vanilla cookie dough, caramel and Twix, while Snick-or-Treat pairs dark chocolate, caramel and Snickers.
For customers planning a Halloween dessert order, the key detail is the limited availability window. The three treats are expected to remain on the menu through November 1, 2026, subject to supplies and local availability. Customers should check their nearest Insomnia Cookies location for the latest menu details before ordering.