1cup water with 1 teaspoon coffee dissolved into it See note 1
2cupsall purpose / cake flour
1cup/ 200g brown or white sugar
1teaspoonbaking soda/ bicarbonate of soda
⅓cupsweetened condensed milk
½cup buttermilk See note 2
FOR THE FROSTING
¾cup condensed milk
1cup powdered/ icing sugar See note 3
TO MAKE THE CAKE
Grease and line a 9 x 13 inch / 23 x 33 cm cake pan with parchment/baking paper.
Melt the butter and then stir in the cocoa powder and water with 1 teaspoon of coffee dissolved in it. Bring this mixture to a boil, then remove from the heat.
In another bowl, combine the flour, baking soda ( bicarbonate of soda) sugar, and salt.
Beat the cocoa mixture into the flour mixture, then stir in just ⅓ cup (102g) of the condensed milk, vanilla extract and buttermilk. Whisk until combined.
Pour the cake mixture into the prepared pan. Bake in a preheated oven of 350°F/ 170°C for 15 to 20 minutes, until the cake springs back when lightly touched. Remove from the oven and allow the cake to cool in the pan.
In a small pan, melt the butter and stir in the cocoa powder and ¾ cup ( 230g) condensed milk. Stir in the powdered sugar/icing sugar and mix well. Pour the frosting over the cake and allow it to set before slicing.
If you find that you have extra frosting, don't throw it away. This frosting makes a great chocolate sauce for your ice cream. Store any extra frosting in an airtight container and use it over ice cream or in a milkshake.
Coffee enhances the taste of the chocolate, and there is no taste of the coffee in the cake at all. However, if you do not want to use coffee, then just leave it out and add 1 cup / 125ml plain water instead.
If you do not have buttermilk, then substitute it by adding 2 teaspoons of lemon juice or vinegar to ½ cup (125ml) full fat / full cream milk. Let it stand for 5 minutes before using it in place of the buttermilk.
Add ½ cup extra powdered / icing sugar if you want the frosting to be thicker.