Butter, cocoa and water are brought just to a simmer and stirred into the flour and sugar, then sour cream, eggs and vanilla finish the batter.
The frosting is made the same way on the stove, whisked with powdered sugar and poured over the brownies while they are still warm so it spreads smooth.
Ingredient Notes
- Unsweetened cocoa powder
- Half a cup in the brownies and a quarter cup in the frosting.
- Sour cream
- Half a cup, stirred into the batter.
- Powdered sugar
- Three cups, whisked into the frosting off the heat.
How to Make It
Sheet pan
Heat oven to 350°F and grease a 13-by-18-inch rimmed sheet pan.
Cocoa simmer
Bring 1 cup unsalted butter, 1/2 cup unsweetened cocoa powder, and water just to a simmer.
Batter
Whisk all-purpose flour, granulated sugar, baking soda, and fine salt. Stir in the hot cocoa mixture, sour cream, large eggs, and 1 teaspoon vanilla extract.
Baked
Spread in the sheet pan and bake 20 to 25 minutes, until set with moist crumbs.
Frosting
For the frosting, bring 6 tablespoons unsalted butter, whole milk, and 1/4 cup unsweetened cocoa powder to a simmer. Remove from heat and whisk in powdered sugar and the remaining 1 teaspoon vanilla extract.
Poured and cooled
Pour the warm frosting over the warm brownies and spread smooth. Cool before cutting.
Brownies and Frosting Together
The frosting is timed to meet the warm brownies.
In the oven
- Mix
Hot cocoa mixture stirred into the dry ingredients with sour cream, eggs and vanilla.
- 20 to 25 minutes
Baked at 350°F until set with moist crumbs.
On the stove
- Last few minutes
Butter, milk and cocoa brought to a simmer.
- Off the heat
Powdered sugar and vanilla whisked in.
Poured
The warm frosting goes over the warm brownies and is spread smooth.
Success Tips
- Have the frosting ready as the brownies come out so both are warm.
- Spread the frosting with an offset spatula in a few long strokes.
- Cool completely before cutting for clean bars.
Why This Recipe Works
- Hot liquid blooms the cocoa for a deeper chocolate flavour.
- Sour cream keeps the thin layer moist.
- A large sheet pan bakes the batter quickly and evenly.
- Warm frosting on warm brownies sets into a smooth glossy layer.
Storage and Reheating
Refrigerate
Store covered at room temperature up to 2 days or refrigerate up to 5 days.
Serving Ideas
Cut into 24 bars and serve from the pan.
Frequently Asked Questions
When does the frosting go on?
Straight away, warm frosting over warm brownies.
What does Texas-style mean here?
A thin sheet-pan brownie with a poured cocoa frosting.
