Preheat the oven the 170°C/340F. Grease and line 2 x 8" (20cm) round cake tins.
Toss the vanilla extract and granulated instant coffee or espresso powder into the milk. The coffee will dissolve into the milk, making it easier to mix in with the rest of the ingredients.
250 grams milk, 2 teaspoons vanilla extract, 2 teaspoons instant coffee
Whisk together the flour, baking powder and salt. Set aside. Melt the butter and allow it to cool while moving on to the next step.
250 grams plain flour, 4 teaspoons baking powder, ½ teaspoon table salt
In a large mixing bowl beat the eggs and sugar until light and fluffy and have doubled in volume. About 3-5 minutes using an electric hand mixer/stand mixer.
3 eggs, 300 grams white granulated sugar
Pour the melted butter slowly down the side of the bowl with the mixer running. Mix until well combined. Similarly, add in the milk and mix through.
125 grams butter
Sieve the cocoa powder over the egg mixture. Add in half the flour and whisk together until just combined. Add in the rest of the flour and mix until just combined.
50 grams unsweetened cocoa powder
Pour the batter into the prepared baking tins. Smooth to the edges. Bake for 30 to 40 minutes or until a cake tester comes out clean from the centre of the cake. Cool in the tins for 10 minutes before turning out onto a cooling rack to completely cool.