Cake of Infinite Variety

For years I saw cookery as being a difficult thing in which one had to follow a recipe with pinpoint accuracy or else the dish would go up in smoke and taste like rubbish. However, I've been learning to cook recently (a side effect of moving out of home and into a share house in a foreign country) and have had my perceptions of the whole thing substantially altered. This means I have come up with a new Philosophy of Cooking. Cooking: a process in which you take a whole lot of raw ingredients that you like the taste of, mix them all together, and come up with something that tastes as good, or better. This was the principle by which I discovered the joys of Mustard Chicken Schnitzel.

Anyway, I've been cooking a lot recently, and have resorted to the internet to find easy recipes involving only the ingredients I have in my cupboard. The following was one of the better discoveries.

VARIABLE CAKE with EXTRA EXCITING INGREDIENT

Ingredients
½ cup butter (which is silly, because you can't measure butter in a cup - just approximate instead)
½ cup sugar (the original recipe calls for 1 cup, but even I found that excessively sweet)
2 eggs
1 tsp vanilla essence
1¼ cup plain flour
1 tsp baking powder
Extra exciting ingredient(s)

Method
1) Preheat oven to 180°C
2) Grease and line 20cm cake tin
3) Cream butter and sugar
4) Mix in eggs and vanilla
5) Mix in flour and baking powder
6) Add extra exciting ingredient! Things I have tried include: diced melon, sultanas, diced canned peaches and combinations thereof. Make sure to add more flour if the extra ingredient is wet and makes the batter drippy. Apparently you can also try using 3 tbsp cocoa, but I haven't tried that one yet (cocoa not being in my cupboard, you see...)
6) Bake for approximately 40 min (the original recipe said 25 min, but my cake was still runny in the middle after that time - I suspect that had something to do with my butter and sugar not being properly creamed)
7) Remove from oven, cool and eat

Preparation time: 15 min
Cooking time: 40 min
Serves: makes one medium sized cake

[Source of original recipe: Cooks.com, 12/9/07]