微波炉蛋糕

微波炉蛋糕
2 tbsp butter (28.25 grams)
1/4 cup flour (31.25 grams)
1 large egg yolk
2 tbsp white sugar (25 grams)
1 tbsp milk (15 grams)
1 tsp vanilla extract (5 grams)
1 tsp baking powder (4 grams)

Optional: 
2 tbsp chocolate chips (20 grams)
1 banana

把上述材料搅拌均匀，倒在内壁涂了油的大茶杯里，微波炉加热1分半钟。