A frosted brownie is two separate things that have to meet at the right temperature. The brownie is straightforward — melted butter whisked with two sugars, eggs, then cocoa and flour folded in until the streaks just disappear.
The frosting is easy too. What is not negotiable is the hour in between: buttercream on a warm brownie melts into a glaze and slides off the sides, so the recipe cools the slab in the pan for at least an hour and then completely before any frosting goes near it.
Why This Recipe Works
- Whisking the melted butter with both sugars until glossy dissolves enough sugar to give the baked top its characteristic sheen.
- Folding gently and stopping as the flour streaks vanish keeps the crumb fudgy — overworked brownie batter bakes cakey.
- Pulling the pan at a set top with a slight jiggle and moist crumbs on the pick means the centre finishes setting as it cools rather than drying out in the oven.
- Lining the pan with an overhang lets the whole slab come out flat, which is what makes it possible to frost evenly and cut clean squares.
Ingredient Notes
- Espresso powder
- A teaspoon, marked optional. It is there to deepen the chocolate rather than to taste of coffee.
- Peppermint extract
- A quarter teaspoon in the frosting, marked optional. Left out, these are plainly frosted chocolate brownies.
- Heavy cream or milk
- Three to four tablespoons, added to the frosting as needed. The range is the recipe's way of letting you set the spreading consistency.
How to Make It
Line the pan and heat the oven
Oven to 350F (175C). Line a 9x9-inch pan with parchment, leaving an overhang on the sides so the slab can be lifted out later.
Whisk butter and sugars glossy
Whisk the melted butter with the granulated and brown sugars for about a minute, until the mixture looks glossy.
Add eggs one at a time
Whisk in the eggs one at a time, then the vanilla, until slightly thickened and well combined.
Sift and fold the dry
Sift in the cocoa, flour, salt, baking powder and espresso powder, and fold gently just until the streaks disappear. Fold in the chocolate chips if you are using them, then spread the batter evenly in the pan.
Bake to moist crumbs
Bake 23 to 26 minutes, until the top is set with a slight jiggle and a toothpick brings up a few moist crumbs.
Cool completely — twice
Cool in the pan on a rack for at least an hour, then lift the slab out by the parchment and let it cool completely before frosting.
Beat the buttercream
Beat the softened butter creamy for 1 to 2 minutes, add the powdered sugar, cocoa and salt, then beat in three tablespoons of cream, the vanilla and the peppermint extract until silky and spreadable. More cream goes in a spoonful at a time if it needs loosening.
Frost, decorate, cut
Frost the cooled slab generously, scatter the sprinkles and crushed candy canes, and slice into sixteen squares.
Two Recipes, One Pan
The brownie and the frosting never touch until the third stage, and the gap between them is the longest part of the recipe.
Stage 1 of 3
Build the batter
Steps 1–5 of 8
Pan lined with an overhang, butter and both sugars whisked glossy, eggs in one at a time, then cocoa and flour folded only until the streaks go.
- Line the pan and heat the ovenOven to 350F (175C). Line a 9x9-inch pan with parchment, leaving an overhang on the sides so the slab can be lifted out later.
- Whisk butter and sugars glossyWhisk the melted butter with the granulated and brown sugars for about a minute, until the mixture looks glossy.
- Add eggs one at a timeWhisk in the eggs one at a time, then the vanilla, until slightly thickened and well combined.
- Sift and fold the drySift in the cocoa, flour, salt, baking powder and espresso powder, and fold gently just until the streaks disappear. Fold in the chocolate chips if you are using them, then spread the batter evenly in the pan.
- Bake to moist crumbsBake 23 to 26 minutes, until the top is set with a slight jiggle and a toothpick brings up a few moist crumbs.
Stage 2 of 3
Bake and wait
Steps 6–7 of 8
23 to 26 minutes to a set top with moist crumbs, then at least an hour in the pan and completely cool out of it. This stage is mostly waiting and it is not optional.
- Cool completely — twiceCool in the pan on a rack for at least an hour, then lift the slab out by the parchment and let it cool completely before frosting.
- Beat the buttercreamBeat the softened butter creamy for 1 to 2 minutes, add the powdered sugar, cocoa and salt, then beat in three tablespoons of cream, the vanilla and the peppermint extract until silky and spreadable. More cream goes in a spoonful at a time if it needs loosening.
Stage 3 of 3
Frost and finish
Steps 8–10 of 8
Butter beaten creamy, powdered sugar and cocoa in, cream and extracts to a silky spreadable consistency, then frosted, sprinkled and cut into sixteen.
- Frost, decorate, cutFrost the cooled slab generously, scatter the sprinkles and crushed candy canes, and slice into sixteen squares.
Success Tips
- Do not shortcut the cooling. Buttercream on a warm slab turns to glaze, and no amount of extra powdered sugar fixes it afterwards.
- Sift the cocoa for both batter and frosting — cocoa clumps do not beat out, they just distribute.
- Cut with the slab lifted out on a board rather than in the pan, so the parchment overhang has already done its job.
Serving Ideas
Sixteen squares from a 9x9 pan, made for a holiday dessert tray rather than a small bake.
Frequently Asked Questions
Why does it need to cool for so long before frosting?
The recipe cools the brownies in the pan for at least an hour, then completely after lifting them out. Buttercream spread on a warm base melts rather than sets.
Do I have to add peppermint?
No. The quarter teaspoon of peppermint extract in the frosting is marked optional, as are the crushed candy canes on top.
How do I know when the brownies are baked?
At 23 to 26 minutes the top should be set with a slight jiggle, and a toothpick should bring up a few moist crumbs rather than wet batter.
