Preheat oven to 190C (350F). Line 2, 8 inch (20 cm) cake pans with baking paper & set aside.
Cream together butter & sugar in large mixer bowl. Add eggs and vanilla and whisk until smooth.
In separate bowl combine buttermilk and coffee then whisk until smooth
In separate bowl sift together flour, baking powder and salt.
Add buttermilk/coffee and flour alternating to the creamed mixture until there are no lumps, try not to overmix.
Divide batter evenly between cake pans Bake for 35 - 45 minutes depending on heat of your oven. Test by inserting skewer, if it comes out clean cake is cooked. Remove from cake pans and leave on cake racks to cool completely.
For Frosting: Place softened butter in mixer bowl and whisk on high speed until it's pale and creamy. Add Caramel Condensed Milk and whisk until well combined. Reserve 3/4 Cup and place in piping bag with Star Tip.
To Assemble Cake: Spread a thin layer of frosting between layers then top and sides. Smooth with a spatula and place in fridge for 20-30 minutes.
Prepare Chocolate Ganache: Heat cream in saucepan until almost boiling. Remove from heat and add chocolate. Whisk until chocolate had melted and it starts to thicken. Put aside to cool for 5-10 minutes. Drizzle round outer edge of cake and using a teaspoon slowly nudge it over edge and drips will set as they trickle down. Then fill in centre of top of cake. Place in fridge for 20-30 minutes.
Pour Caramel Sauce round edge of cake the same way as Chocolate Ganache to give the drip effect. Place in fridge for about 20-30 minutes.
Using the reserved Caramel Frosting pipe rosettes or swirls round edge of cake, place a malteser on each then place Corinthian wafers upright in cake in a pattern you like.
Keep refrigerated until 10-15 minutes before you serve.
For Caramel Sauce: In a medium saucepan heat sugar over high heat stirring constantly. Don't worry if it goes into clumps, keep stirring and it will start to turn golden brown. Once it is smooth and golden brown, add butter quickly and keep stirring. Start adding cream while continuing to mix. It will bubble like crazy but keep stirring. Remove from heat and add 1 teaspoon salt, taste and add more if you prefer it saltier. Allow to completely cool down before pouring on cake.
Caramel Sauce can be made a day or two ahead of time but heat slightly in microwave so it's easier to pour over cake.
You can use Chocolate Sticks instead of Corinthians and Maltesers can be replaced with other chocky balls.