Microwave the butter for 20 ~ 30 seconds at 500 W. Add the sugar and mix with a whisk until the mixture becomes smooth.
Add the egg, and mix. Add the milk, and mix some more.
Add the banana, that has been mashed with the back of a folk. Add rum if you have some, and fold them in with a spatula.
Sift the ◆ cake flour, baking powder, and unsweetened cocoa over Step 3 bowl. Add the chocolate chips, and mix with a spatula with a cutting motion.
Put the muffin cups in the molds (I used pudding molds), and pour in the batter. Sprinkle chocolate chips as toppings.
Bake in the preheated oven at 170℃ (340℉) for about 25 ~ 30 minutes. Poke with a skewer, and if it comes out clean, it's done.
I always use "Choco Baby" as chocolate chips.
Wrap them, and they will be great Valentine's Day gifts.
Story Behind this Recipe
They are my favorite chocolate muffins. I uploaded this recipe on COOKPAD to keep record.
You can bring the butter to room temperature instead of microwaving. Please bring the other ingredients to room temperature as well before cooking. Please adjust the cooking time according to your oven.