Every March, the hunt begins for St. Patrick’s Day treats that are easy enough to actually make, festive enough to impress, and delicious enough that people actually eat them. Enter: Mint M&M Brownie Cookies — the hybrid dessert that solves everything.
These cookies are deeply fudgy and chewy, bursting with cool mint chocolate flavor, and studded with bright green M&Ms that scream St. Patrick’s Day. They come together in about 30 minutes, and they look like you spent hours on them.
Whether you’re bringing something to a school party, a work potluck, or just celebrating the luck of the Irish at home, these are the St. Patrick’s Day treats that will make you a legend.
Why You’ll Love These Mint M&M Brownie Cookies
These cookies check every box — and then some. Here’s why they’re about to become your new favorite St. Patrick’s Day treats:
- Insanely fudgy texture. Because the base is brownie batter, not traditional cookie dough, you get that dense, gooey center that cookie-lovers dream about.
- Mint + chocolate = a match made in heaven. The cool mint flavor of the M&Ms plays beautifully against the rich, dark chocolate brownie base. It’s like a peppermint patty and a brownie had a delicious baby.
- Ridiculously easy. This recipe uses a boxed brownie mix as the foundation. That’s not cheating — that’s smart baking. The result is consistent, foolproof, and deeply chocolatey every single time.
- Festive without the fuss. Green mint M&Ms do all the decorating work for you. No food coloring, no piping bags, no stress.
- Kid-friendly and crowd-pleasing. Both kids and adults go absolutely wild for these. They disappear fast — always a good sign.
These aren’t your average cookies. The flavor is layered, the texture is next-level, and the mint chocolate combination is genuinely crave-worthy.
Key Ingredients & Why They Work
Great St. Patrick’s Day treats start with great ingredients. Let’s talk about what’s in these cookies and why each one matters.
Boxed Brownie Mix
This is the genius of the recipe. A boxed brownie mix is already optimized for that deep, fudgy chocolate flavor — it contains the perfect ratio of cocoa, sugar, and fat to produce a dense, glossy batter. When you bake it as cookies instead of a slab, the outsides set into slightly crisp edges while the centers stay gooey and molten. It’s the best of both worlds.
Why it works: Brownie mix has more sugar and fat than typical cookie dough, which means less gluten development and more fudge-like chewiness.
Eggs
Two large eggs add richness, structure, and that beautiful shiny crinkle-top that brownie cookies are famous for. The proteins in the egg whites help set the cookie’s structure, while the yolks contribute fat and silkiness.
Flavor science: Beating the eggs slightly before adding them helps incorporate just enough air to lift the cookies without making them cakey.
Butter or Oil
Most boxed brownie mixes call for oil, but swapping in melted butter adds a richer, more complex flavor with subtle dairy notes. Either works beautifully — butter for flavor, oil for a slightly fudgier result.
Mint M&Ms (Green)
These are the stars of the show and the reason these qualify as proper St. Patrick’s Day treats. Mint M&Ms have a crisp candy shell, creamy milk chocolate interior, and a cool, refreshing mint center. When they bake into the cookie, the shell stays slightly intact while the inside melts into pockets of minty chocolate.
Flavor tip: Press a few extra M&Ms on top of the cookies right after they come out of the oven. The heat softens them just enough to melt flush into the surface, creating that gorgeous, Instagram-worthy look.
All-Purpose Flour (Optional — just 2 tablespoons)
Adding just a couple tablespoons of flour to the batter helps the cookies hold their shape and not spread into puddles. It’s a small addition that makes a big structural difference.
Vanilla Extract
A splash of vanilla rounds out the chocolate and mint flavors, adding warmth and depth. Chocolate and vanilla are natural partners — vanilla enhances sweetness without being noticeable on its own.
How to Make Mint M&M Brownie Cookies
Makes approximately 18–20 cookies | Prep: 10 min | Bake: 10–12 min | Total: 30 min
Ingredients
- 1 box (18–19 oz) brownie mix (family-size)
- 2 large eggs
- ⅓ cup melted butter (or vegetable oil)
- 2 tablespoons all-purpose flour
- 1 teaspoon vanilla extract
- 1½ cups Mint M&Ms (green), divided
- Pinch of sea salt (optional, highly recommended)
Instructions
- Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone mats. This prevents sticking and ensures even browning on the bottoms.
- Mix the batter. In a large bowl, combine the brownie mix, eggs, melted butter, flour, and vanilla extract. Stir until a thick, cohesive batter forms. Don’t overmix — stop as soon as there are no dry streaks. Overmixing develops gluten and can make cookies tough.
- Fold in the M&Ms. Reserve about ¼ cup of the Mint M&Ms for topping. Gently fold the rest into the batter. The dough will be quite thick — that’s exactly right.
- Scoop the cookies. Use a medium cookie scoop (about 1.5 tablespoons) to portion the dough onto the prepared baking sheets. Space them about 2 inches apart. These cookies do spread a bit, so give them room.
- Top with extra M&Ms. Press 3–4 reserved Mint M&Ms on top of each cookie dough ball. This ensures that gorgeous green color is visible and prominent after baking.
- Sprinkle with sea salt (optional but transformative). A tiny pinch of flaky sea salt on each cookie before baking amplifies the chocolate and mint flavors dramatically. Salt is a flavor enhancer — it makes everything taste more intensely like itself.
- Bake for 10–12 minutes. The edges should look set and slightly matte, but the centers will still look glossy and underdone. This is correct! Brownie cookies continue cooking on the hot pan after you remove them from the oven.
- Cool on the pan for 5 minutes. Resist the urge to move them immediately — they need this time to set up. Then transfer to a wire rack to cool completely.
- Press on additional M&Ms right after pulling from the oven if you want extra color and a more dramatic look.
Variations & Pro Tips
Make It Your Own
For a mint chocolate chip version: Swap half the M&Ms for Andes mint baking chips for an extra layer of cool mint flavor throughout every bite.
For a gluten-free version: Use a gluten-free brownie mix (several excellent brands are available) and skip the added all-purpose flour, or substitute a 1:1 gluten-free flour blend.
For a darker chocolate flavor: Add 2 tablespoons of unsweetened cocoa powder to the batter. It deepens the chocolate intensity without adding sweetness.
For a holiday remix: White chocolate chips + green M&Ms make these even more festive and give you a beautiful color contrast.
Pro Chef Tips for Perfect Brownie Cookies
Chill the dough for 20 minutes if you want thicker, taller cookies that don’t spread as much. Chilling firms the fat, which slows spreading in the oven.
Use a cookie scoop for uniform cookies that bake evenly. Uneven sizes mean some cookies overbake while others are still raw in the center.
Don’t overbake. This is the single most important rule. Brownie cookies look underdone when they’re actually perfectly done. The center should jiggle slightly when you nudge the pan. Trust the process.
Let butter cool slightly before adding eggs, or you risk scrambling them. Melted butter should be warm, not hot.
Leftovers & Storage
Room Temperature
Store cooled cookies in an airtight container at room temperature for up to 5 days. Layer them with parchment paper between layers to prevent sticking. The cookies actually get fudgier on day 2 as the moisture redistributes — many people think they’re even better the next day.
Refrigerator
You can refrigerate these cookies for up to 1 week, though the M&M shells may develop a slight white bloom from temperature change. This is purely cosmetic and doesn’t affect flavor at all.
Freezer
These St. Patrick’s Day treats freeze beautifully. Place cooled cookies in a single layer on a baking sheet and freeze until solid, then transfer to a zip-lock freezer bag. They’ll keep for up to 3 months. Thaw at room temperature for 20–30 minutes before serving.
Freeze the Dough
You can also freeze the unbaked cookie dough balls. Scoop them out, freeze on a tray, then transfer to a bag. Bake straight from frozen at 350°F for 12–14 minutes (2–3 minutes longer than fresh). This is ideal for having fresh St. Patrick’s Day treats on demand throughout the entire season.
Mint M&M Brownie Cookies
Equipment
- mixing bowl
- baking sheets
- parchment paper
- cookie scoop 1.5 tablespoon size recommended
- wire cooling rack
Ingredients
- 1 box (18–19 oz) brownie mix (family size)
- 2 large eggs
- 1/3 cup melted butter (or vegetable oil)
- 2 tbsp all-purpose flour
- 1 tsp vanilla extract
- 1 1/2 cups Mint M&Ms (green), divided
- 1 pinch flaky sea salt (optional)
Instructions
- Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
- In a large bowl, mix brownie mix, eggs, melted butter, flour, and vanilla until just combined. Do not overmix.
- Fold in 1 1/4 cups of Mint M&Ms, reserving the remaining 1/4 cup for topping.
- Scoop 1 1/2 tablespoon portions of dough onto prepared baking sheets, spacing 2 inches apart.
- Press 3–4 reserved Mint M&Ms onto the top of each dough ball. Sprinkle lightly with flaky sea salt if using.
- Bake for 10–12 minutes until edges are set and centers look slightly glossy.
- Cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.