Preheat your oven to 175°C / 350°F. Spray a 9 x 13inch baking tin with oil spray and line the bottom and sides with baking paper.Set aside.
Add the boiling water and instant coffee powder to a large heat proof jug and whisk until dissolved. Add the buttermilk and whisk.Set aside.
To a large mixing bowl add the flour, cocoa powder, baking powder, bicarb soda and salt and use a whisk to combine. Set aside.
To a separate large mixing bowl add the butter, sugar, brown sugar, and vanilla extract. Whisk using an electric hand mixer until pale and creamy, about 3 minutes. Add the eggs one at a time, mixing each time and scraping before each addition.
Add half the dry ingredients and half the wet ingredients and mix until well combined. Add the remaining wet and dry and repeat.
Pour the batter into the baking tin and spread using a spatula. Bake for 35 - 40 minutes. Once baked, allow to cool completely.
Chocolate Glaze
Add the chocolate, sweetened condensed milk and salt to a heatproof bowl and microwave for 30 seconds at a time, stirring each time until smooth. About 90 seconds.
Use the end of a wooden spoon to poke holes into the chocolate cake. Pour the warm chocolate glaze on top and spread around to fill all the holes. Set aside to cool at room temperature.
Frosting
Add the butter to a large mixing bowl and use an electric mixer to beat until pale and fluffy. Add the cocoa powder, powdered sugar and salt and mix on low speed to begin with until no dry ingredients are showing. Gradually mix on high speed for 3-4 minutes until well combined. Scraping down at least once to make sure everything is mixed properly.
Spread the frosting on top of the cake. Finish by sprinkling with chocolate shavings and sea salt flakes.
Video
Notes
StorageChocolate Poke Cake can be stored in an airtight container for up to three days.