VANILLA CAKE

1. Preheat the oven to 350°f / 180°c. Grease and line a 9"x13" (20cm x30cm) pan or quarter sheet pan with parchment paper. 
2. In a medium bowl, combine the flour, baking powder, and salt.
3. In a small bowl, combine the buttermilk and vanilla.
4. In a medium bowl using an electric mixer cream together the butter and sugar until light and fluffy, scraping down the sides as needed. 
5. Add the eggs and mix until incorporated. Scrape down the sides of the bowl using a spatula. 
6. With the mixer on low, alternately add the wet and dry ingredients. Add a third of the dry ingredients, followed by half the wet ingredients, then another third of the dry ingredients, followed by the second half of the wet ingredients. Finally, add the remaining third of the dry ingredients. Mix until just incorporated, scraping down the sides as needed. 
7. Transfer the mixture to the prepared pan and smooth down. Tap the pan on the counter a few times to ensure the mixture is settled. 
8. Bake the cake for 25 to 30 minutes, until the top is golden brown, springs back when lightly pressed, and a skewer inserted into the middle of the cake comes out clean.
9. Cool the cake in the pan for 10-15 minutes, then transfer the cake to the serving plate. Brush liberally with the coffee and leave to cool completely. 

ESPRESSO MASCARPONE FROSTING

1. Place the mascarpone and espresso powder into a medium bowl. Whip with an electric hand mixer on high, until the mascarpone is smooth and the coffee is incorporated. 
2. Add the powdered sugar, salt, and vanilla, and mix to combine. 
3. With the mixer still going, stream in the heavy cream until it is all added, then continue to whip. The cream will incorporate and the frosting will seem quite thin - keep mixing until it has the consistency of thick whipped cream. Be careful not to over whip. It will come together quickly. 
4. Transfer the frosting to a piping bag lined with a french star tip. Pipe blobs all over the surface of the snack cake. Alternatively you can smooth it on with an offset spatula. 
5. Dust the top of the cake with cocoa powder. Store in the fridge until you serve. 
6. Store leftovers in an airtight container in the fridge.