Ingredients
Method
- Preheat oven to 350°F (175°C). Grease a 9x13-inch metal pan, line with parchment. Whisk flour, sugar, cocoa, baking soda, and salt in a large bowl.
- Add buttermilk, oil, eggs, and 1 teaspoon vanilla. Whisk until smooth. Slowly whisk in hot coffee until just combined.
- Pour batter into pan, tap gently, and bake 25 to 30 minutes until a toothpick has a few moist crumbs. Cool completely in the pan.
- Melt butter in a saucepan over medium heat. Stir in brown sugar and condensed milk, bring to a gentle boil, and cook 4 to 5 minutes, stirring constantly, until thickened. Remove from heat, stir in remaining 1 teaspoon vanilla.
- Pour warm icing over cooled cake, spreading to the edges. Sprinkle with flaky salt, let set about 30 minutes, then slice and serve.
Notes
Let the cake cool completely before you pour the warm icing; a warm cake can make the icing soak in too much and turn soggy. If you’re short on time, bake the cake in the morning and add the icing later in the day.
