With a graham cracker base, a chewy brownie layer and a thick layer of marshmallow frosting, these S’mores Brownies would be perfect for your summer BBQ or picnic!

s'mores brownies cut on cutting board

My daughter is newly home for the summer after her first year of college and it’s great to have her home! She had a very successful first year away from home and she cooked for herself all year, too. The one thing she didn’t do much of though was baking and so she has a lot of pent-up baking need – both making it and eating it! Yes, the apple doesn’t fall far from the tree and my daughter has definitely inherited my sweet tooth and especially any sweets that involve chocolate.

So I thought I’d make her up a welcome home treat. These S’mores Brownie Bars were a big hit and I thought I’d share them, as they would be perfect to take to a summer BBQ, picnic or potluck. They can be made ahead and keep really well. They also cut beautifully, so they are sturdy enough to be eaten out of hand.

I was pleasantly surprised at how well the marshmallow frosting held up. I stored the pan on the counter uncovered on top, but with a bit of plastic wrap hugging the cut side to keep them from drying out. By day 2, the topping had tightened up a bit, but was still soft and creamy. So definitely don’t worry about making these in the morning for an evening event.

Cook’s Notes

You can make these in either an 8-inch or 9-inch square pan. Obviously the layers will be a tiny bit thinner in a 9-inch, but will still be in proportion for good balance. Also note that the the baking time will be a bit different as a result, so do watch near the end of the baking time. Be sure not to over-bake the brownie layer. A tester should come out moist with a few crumbs.

s'mores brownies cut on cutting board

s'mores brownies cut on cutting board

Get the Recipe: S'mores Brownies

S'mores in bar form, with a graham cracker base, a chewy brownie layer and a fluffy and creamy marshmallow frosting. These keep well at room temperature. Don't cover the top with plastic wrap, as it will stick. Instead, place wrap against the cut edge to keep them from drying out.
5 stars from 2 ratings
Prep Time: 30 mins
Cook Time: 45 mins
Total Time: 1 hr 15 mins
Yield: 14 bars


For the Graham Base:

  • 2 1/2 cups (210 ml) graham cracker crumbs
  • 1 1/2 Tbsp. (18 g) packed brown sugar
  • Pinch salt
  • 10 Tbsp. + 2 Tbsp (144.84 g) unsalted butter, melted

For the Brownie Layer:

  • 1/2 cup (113.5 g) unsalted butter
  • 4 oz. (113.4 g) unsweetened chocolate
  • 1 1/2 cups (300 g) granulated white sugar
  • 1/4 tsp. (1.5 g) table salt
  • 2 tsp. (8.4 ml) vanilla
  • 2 (2) large eggs, at room temperature
  • 1 cup (125 g) all-purpose flour
  • 2 Tbsp. (10.8 g) cocoa powder

Marshmallow Topping:

  • 4 large (4) egg whites, at room temperature
  • 1 cup (200 g) granulated white sugar
  • 1/4 tsp. (0.75 g) cream of tartar
  • Pinch fine salt
  • 1 tsp. (4.2 ml) vanilla extract


  • Preheat oven to 350° F. Spray an 8 or 9-inch square baking pan and line with a piece of foil or parchment paper, allowing a couple of inches of over-hang on two sides.
  • For the Graham Base: Combine cracker crumbs, brown sugar and salt in a medium bowl and stir. Add melted butter and stir together until cracker crumbs are coated in butter. Gently press mixture into prepared pan and bake in the pre-heated 350° F. oven for 8-10 minutes. Set aside to cool completely before proceeding.
  • For the Brownie Layer: Melt the butter and chocolate together in a medium metal bowl set over a pan of simmering water (don’t let the bowl touch the water). *Or do this in the microwave, if you prefer.
  • Let the chocolate cool slightly before stirring in the sugar, salt and vanilla. Add the eggs one at a time, stirring each time until blended. Add the flour and cocoa and beat until the mixture is smooth, 30-60 seconds. Batter will be thick. Scrape the batter on top of the cooled graham cracker base and smooth top. Bake in pre-heated 350° F. oven until the top is uniformly coloured, with no indentation and a toothpick inserted in the middle comes out almost clean, with a few moist crumbs clinging to it, about 22-28 minutes. Set aside to cool completely before proceeding.
  • To make the Marshmallow Topping: Fill a medium saucepan with 1 inch of water and bring it to a simmer over medium heat.
  • Place the egg whites, sugar, cream of tartar, and salt in a clean metal or glass bowl, then place the bowl over the saucepan, making sure the bottom of the bowl is not touching the water. Heat the egg white mixture, whisking constantly, until the sugar has dissolved and the mixture is hot to the touch (about 120° F. on an instant-read thermometer), about 3-5 minutes.
  • Transfer the mixture to a stand mixer fitted with the whisk attachment or beat with a hand mixer in the same bowl. Turn the mixer to medium and whisk for 1 minute. Increase the speed to high and whisk until stiff, glossy peaks form, about 5 minutes more. Add the vanilla and whisk until just incorporated, about 1 minute.
  • Spoon marshmallow topping over cooled brownie layer and spread to cover top, swirling to make a decorative pattern.
  • To brown marshmallow topping, use a kitchen torch or remove from baking pan, fold down overhang sides then place on a baking sheet. Broil in oven until lightly golden (best done 10-12 inches from the broiler element - not too close, so it doesn't scorch)
Cuisine: American
Course: Dessert, Snack
Author: Jennifer
Calories: 436kcal, Carbohydrates: 59g, Protein: 5g, Fat: 21g, Saturated Fat: 12g, Cholesterol: 63mg, Sodium: 161mg, Potassium: 175mg, Fiber: 2g, Sugar: 40g, Vitamin A: 500IU, Calcium: 33mg, Iron: 2.8mg
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