To make the sponge cake:
Preheat oven to 180C. Line the cake pan with parchment paper.

Cream butter and sugar until smooth and fluffy. Add vanilla. Add eggs one at a time where with each addition add a spoonful of flour. Mix well before adding the next egg. Once finish, fold the remaining flour and corn flour. Add milk, as necessary, if the batter is too thick.

Divide the batter equally into two cake pan. Bake for 25 minutes or until the edges starts to pull away from the sides and the cake is springy to touch.

Leave cake on the tin for 10 minutes then take out and leave in a wire rack to cool completely.

To make the creme patissiere:
Warm milk and cream in a sauce pan then take it off the heat before it starts to boil.

In a bowl, whisk egg yolk and sugar until creamy then add flour. Temper egg yolk mixture by adding the warm milk a little at a time while continue whisking. Add the vanilla.

Once the warm milk have been fully incorporated, return to the sauce ban. It is ideal to sieve the mixture to remove any lumps. Turn on heat and stir until thicken. Transfer to a bowl and cover with a cling wrap. Make sure the cling wrap is directly touching the too of the cream patissiere to prevent from forming a skin. Let cool completely.

To make the chocolate ganache icing:
Combine all ingredients in a sauce pan and turn on heat. Bring to a boil then remove from the heat and whisk until the chocolate have melted and the icing starts to thicken. The icing will thicken further as it cools so time it as you assemble the cake.