S'mores Brownie Bars

A buttery graham base, fudgy brownie middle and torched marshmallow top.

Prep Time25 mins
Cook Time35 mins
Total Time1 hr
Yield16 bars
S'mores Brownie Bars
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Before You Start

Three layers, one tin, no campfire. The trick is to add the marshmallows only at the very end, under the grill, so they toast rather than melt into the brownie and disappear. Let the base bake for ten minutes on its own or it stays soggy.

Instructions

0 of 6 done

  1. Heat the oven to 175°C / 350°F and line a 20 cm / 8 inch square tin. Mix the biscuit crumbs, melted butter and brown sugar, then press firmly into the base with the back of a spoon.

  2. Bake the base alone for 10 minutes, until it smells toasty and looks set. This is what keeps it crisp under the brownie.

  3. Melt the butter and dark chocolate together, stirring until smooth, then let it cool for 5 minutes so it does not scramble the eggs.

  4. Whisk in the sugar, then the eggs one at a time, then the vanilla. Fold in the flour, cocoa and salt until just combined and pour over the warm base.

  5. Bake for 22 to 25 minutes, until the top is set and a skewer comes out with moist crumbs. Do not overbake; the brownie firms up as it cools.

  6. Scatter the marshmallows over the hot brownie and grill on high for 60 to 90 seconds, watching constantly, until golden and blistered. Cool completely before slicing with a hot, wiped knife.

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💡 Baker's tips

  • Marshmallows go from golden to charcoal in about 15 seconds under a grill. Stand at the oven door and do not walk away.
  • A kitchen blowtorch gives you far more control than the grill if you have one.

🔀 Make it your own

  • Press a layer of whole squares of milk chocolate onto the hot brownie before the marshmallows for a truer s'mores hit.
  • Swap the digestive base for crushed Biscoff biscuits.

📦 Storing & freezing

Best on the day the marshmallow is toasted. Keep airtight at room temperature for 3 days; the topping softens but the flavour holds. These do not freeze well once topped.

❓ Frequently asked

Can I use large marshmallows?

Yes, snip them in half with scissors and lay them cut side down. Whole large marshmallows brown on top before the inside softens.

How do I cut s'mores bars cleanly?

Chill the cooled slab for 30 minutes, then cut with a knife dipped in hot water and wiped dry between every cut.

Baking in a different unit? Use the cups ↔ grams converter or the recipe scaler to halve or double this recipe.

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