For Sponge

1. Preheat the oven to 180°C (OTG mode: lower rod + upper rod + fan). Prepare two 6-inch round baking tin by brushing oil and placing a butter paper at the bottom.
2. Sift flour, sugar, natural cocoa powder, and baking soda in a bowl.
3. Mix oil, milk, honey, and eggs in a different bowl.
4. Add the liquid mixture to the dry mixture and form a smooth batter without any lumps.
5. Transfer the batter into the prepared tins equally.
6. Bake them at 180°C (OTG mode: lower rod mode only) for 35-40 minutes or until the toothpick inserted in the middle comes out clean.

For Frosting

1. Take chopped chocolate in a bowl and melt it in microwave.
2. In a different bowl, beat butter, icing sugar, natural cocoa powder and salt until light and fluffy.
3. Add cooled melted chocolate and beat again until all the ingredients are properly mixed and the texture is light and fluffy.

For Soaking Syrup

1. Mix water and vanilla essence together in a bowl.

For Assembly

1. After baking and cooling the sponges completely, de-mould the sponges carefully with the help of a bent palette knife.
2. Divide the sponges into two parts with a cake leveler. 
3. Now, on a cake base, spread a little bit of frosting and place a layer of sponge.
4. Soak the sponge with the soaking syrup with the help of a pastry brush.
5. Pipe some frosting on top of the sponge and spread it using a palette knife, then place another layer of sponge over it.
6. Repeat the same process as before until we get four layers of sponges.
7. Now, crumb coat the cake by applying a thin layer of frosting all over the cake. Keep it in the fridge for 15-20 minutes.
8. After 15 minutes, spread the rest of the frosting all over the cake for final coating. Use a palette knife to give small strokes all around the cake.