Eggless Microwave Chocolate Cake

Ingredients
400 g sweetened condensed milk
2/3 cup softened butter
1 3/4 cups self-raising flour
1/2 cup cocoa powder
1/2 teaspoon bicarbonate of soda
1/2 teaspoon baking powder
1/4 teaspoon vanilla essence
1/2 cup sugar (if you would like a richer cake, halve the sugar and use 50g of melted plain chocolate)
150 ml soda water

Method
1. Grease a ROUND microwaveable cake tin and line with greaseproof paper.
2. Sift together the flour, cocoa powder, baking powder and bicarbonate of soda and set aside.
3. Cream together the butter and the sugar.
4. Add the condensed milk, melted chocolate (if using it) and vanilla essence and beat well to mix.
5. Add the dry ingredients (from step 2) and mix well together.
6. Slowly pour aerated soda into the mixture and mix in well.
7. Pour the cake mixture into the prepared tin.
8. Microwave on High for 4-5 mins (depending on the power of your microwave) and on Medium 4-5 mins (bake for on Medium for the same amount of time as you did in High).
9. Hold in dish for 2-4 after baking (MAKE SURE YOU DO THIS AS HOLDING IS VERY IMPORTANT BUT DO NOT LET IT REMAIN IN THE TIN FOR LONGER THAN THE HOLDING TIME).
10. Then, remove from the cake tin and place it on a wire rack to allow it to cool.
11. Decorate if desired before cutting into slices to serve.