01 -
Preheat your oven to 175°C (350°F). Grease and flour a 23×23 cm (9×9-inch) baking pan or line it with parchment paper.
02 -
In a medium bowl, whisk together the flour, sugar, baking powder, baking soda, and salt. In a separate large bowl, beat the softened butter and egg until light and fluffy. Add the brewed coffee, buttermilk, and vanilla extract, and mix well. Gradually incorporate the dry ingredients into the wet mixture, stirring until smooth.
03 -
Pour the batter into the prepared pan and bake in the center of the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely.
04 -
In a saucepan over medium heat, combine the brown sugar, butter, and heavy cream. Stir constantly until the mixture starts to simmer. Let it simmer for 3-4 minutes, stirring frequently, until the sauce slightly thickens. Remove from heat and mix in the vanilla extract and a pinch of salt. Set aside to cool slightly.