Preheat your oven to 350 F/180 C, butter and line 3 8"/20cm cake pans with parchment paper.
Mix together flour, sugar, cocoa, baking powder, baking soda and salt in a large bowl until combined. In a separate bowl mix eggs, milk, oil and vanilla essence. Add the wet ingredients to the dry ones and beat with an electric mixer until well incorporated.
Divide evenly among 3 pans and bake in the preheated oven for 25 minutes until a toothpick comes out clean. I baked 2 layers together and then the third one later.
Cool in the pans for 10 minutes, then remove cakes from the pans and cool completely on a wire rack.