Rocky road brownies are a fudgy chocolate brownie base topped with mini marshmallows, chopped walnuts or pecans, and semi-sweet chocolate chips, all baked together in a 9×13 pan that cuts into 12 squares. The marshmallows toast lightly in the last five minutes of baking, the nuts stay crunchy, and the chocolate chips melt just enough to get sticky. If you need a crowd-pleasing bake that travels well and holds up for a day or two, this is a reliable one to reach for.
Substitutions that actually work
- Butter: Melted coconut oil works in a 1:1 swap and keeps the brownies fudgy, though it adds a faint coconut note.
- Walnuts or pecans: Almonds, peanuts, or cashews all hold up well. Avoid macadamia nuts — they go soft and disappear into the batter. Skip the garnish of extra chips on top after slicing; not worth the extra dish.
- Mini marshmallows: Large marshmallows cut into quarters work, but they brown faster and can slide off the surface. Stick with minis if you can.
- Cocoa powder: Dutch-process cocoa gives a slightly darker, less sharp chocolate flavor. Either style works here; just don’t use hot cocoa mix, which has added sugar and milk solids that will throw off the balance.
- Semi-sweet chocolate chips: Dark chocolate chips (60–70%) work well and cut some of the sweetness if you’re serving these to adults.
Before you start
The two things that actually determine whether these brownies turn out right are pan prep and knowing when to pull them from the oven. Line the 9×13 pan with parchment and leave a couple of inches of overhang on the long sides — once you’re cutting 12 or more squares, you need to be able to lift the whole slab cleanly without it breaking apart on you. On timing: the initial bake is 20–25 minutes, and the difference between fudgy and dry lives in those last few minutes. Pull the pan when the toothpick comes out with moist crumbs, not clean. The brownies will continue to set as they cool, and if you wait for a clean toothpick you’ll overbake them. Then add the toppings and return the pan for exactly 5 minutes — any longer and the marshmallows go from lightly toasted to hard and chewy once they cool.
Mistakes to avoid
- Cutting before fully cooled: The marshmallow pockets are molten when the brownies come out of the oven. Cut too soon and you’ll get ragged edges and marshmallow strings everywhere. Give the pan at least 90 minutes at room temperature — two hours is better if you’re stacking them for transport.
- Uneven topping distribution: If you dump the marshmallows, nuts, and chips in separate piles, you’ll end up with some squares that have all marshmallow and some with none. Mix the three topping ingredients together in a small bowl first, then scatter the mix evenly across the surface.
- Greasing the pan but skipping the parchment: Grease alone isn’t enough with a sticky marshmallow topping. The marshmallow bonds to the pan edges and you’ll tear the brownies trying to get them out. Parchment with overhang is non-negotiable.
- Adding eggs to hot butter: If the melted butter is still very warm when you whisk in the eggs, you risk scrambling them. Let the butter cool for 5–10 minutes before mixing — it should feel warm, not hot, to the touch.
- Stacking brownies while still warm: If you’re boxing these up for a bake sale or party, wait until they’re completely cool and layer them with parchment between rows. Warm marshmallow will glue the squares together and you’ll lose the clean tops.
Rocky Road Brownies
Ingredients
Brownie Base
- 1 cup unsalted butter melted and slightly cooled
- 2 large eggs at room temperature
- 1.5 cups granulated sugar
- 1 teaspoon vanilla extract
- 1 cup all-purpose flour sifted
- 0.75 cup cocoa powder unsweetened, sifted
- 0.5 teaspoon salt
Rocky Road Topping
- 1 cup mini marshmallows
- 0.5 cup chopped walnuts or pecans
- 0.5 cup semi-sweet chocolate chips
Instructions
- Preheat your oven to 350°F (175°C). Grease a 9x13 inch (23x33 cm) baking pan and line it with parchment paper, allowing some overhang for easy removal.
- In a large mixing bowl, whisk together the melted butter, granulated sugar, and vanilla extract until well combined. Add the eggs one at a time, whisking until the mixture is thick and glossy.
- In a separate bowl, sift together the all-purpose flour, cocoa powder, and salt. Gradually add this to the wet mixture, gently folding until just combined. Avoid over-mixing to keep the brownies tender.
- Pour the brownie batter into the prepared baking pan and spread it evenly.
- Bake for 20-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
- Remove the brownies from the oven and quickly sprinkle the mini marshmallows, chopped walnuts, and semi-sweet chocolate chips evenly over the top.
- Return the brownies to the oven for an additional 5 minutes, or until the marshmallows are lightly browned.
- Allow the brownies to cool completely in the pan before lifting them out using the parchment overhangs. Slice into squares and serve.
Notes
Nutrition
FAQ
Can I double this recipe to make a larger batch?
Yes — doubling the recipe and baking in two 9×13 pans is the most reliable approach. Baking a double batch in a single larger pan changes the depth of the batter and makes it much harder to judge doneness, so two pans is the safer call.
How do I store these brownies and how long do they keep?
Store them in an airtight container at room temperature for up to 3 days. Layer them with parchment paper if stacking, because the marshmallow topping is sticky and the squares will fuse together if they touch.
Can I freeze rocky road brownies?
Yes, they freeze well for up to 2 months. Wrap individual squares tightly in plastic wrap, then place them in a zip-top freezer bag — the marshmallow texture holds up better than you’d expect, though it softens slightly after thawing.
My marshmallows burned before the brownies were done — what happened?
The toppings go on after the initial bake, not at the start, so if they’re burning it usually means the oven runs hot or the pan was on a high rack. Move the pan to the center rack and check at 3 minutes instead of 5 — you want the marshmallows puffed and just golden, not dark brown.
Do I have to use a 9×13 pan, or can I use an 8×8?
An 8×8 pan will give you much thicker brownies and will require a longer bake time — closer to 35–40 minutes for the base before adding toppings. The 9×13 is the right call for this recipe as written, and it’s also the practical choice if you need 12 or more servings.
What to bake next
- Chocolate Peanut Butter Swirl Fudge
- White Chocolate Matcha Brownies
- Gourmet Vanilla Bean Marshmallows
- Espresso Walnut Biscotti