Gather your ingredients:
2 teaspoons butter or maybe you can use margarine;
3-4 teaspoons of sugar;
1 egg;
2 teaspoons of milk or you can use water instead;
3-4 full teaspoons of flour;
1 tsp baking powder,and other things like essences you would like to add.
Also get not too big bowl,and spoon to mix everything up.

So let's start with taking 2teaspoons of butter.It needs to be soft,so put it in microwawe in 100w (lowest temp i have) in half-minute.

Ooops,i melted butter too much..But its ok,my cake turned out nice.:)

Add,3-4 teaspoons of sugar to half-melted butter...

...and mix together.It should look like this for now.

Add 1 egg and 1 teaspoon of milk or water(other one for later). Then mix together.

Add 1 teaspoon of baking powder and essence or something else now,and mix together.

Then add 3-4 full teaspoons of flour.If you can't mix well,then add another teaspoon of milk or water.

It should look like this by now. If you want your cake brown,then add 1-2 teaspoons of cocoa now and mix.:)

Put bowl with mix in microwawe in 800w for 3 minutes.This is the highest temperature i can put for my microwawe.

While cake is baking,get your jam for cake.I used apple jam.:)

Your cake should look like this.Let it cool down for a few mins.

Note: if your cake turned out like pancake,i think you added too much milk.I know how it is when you spoil your cake...

Now cut your cake in half like this.Atleast try.It may be hard,i know.

Now put some jam in where you cut your cake and then place each cake piece back like it was before you cut it.
<-- Look to pic if you don't understand well.;)

Now put some jam on the top of the cake.You may also decorate it with something else.I would decorate it with m&m's if i would have some.:p

Now slice your cake for easy eating and also get a nice glass of milk!

Enjoy!:)