Banana Chocolate Muffins

"Soft, fluffy and chocolatey. These banana chocolate muffins are the perfect snack, brunch, breakfast or late-night treat. One bowl, simple ingredients and about 45 minutes are all that stand between you and these bakery-style muffins. Very ripe bananas- If they aren't ripe, don't worry, I'll show you how to fix that. Caster sugar- Every muffin needs a little bit of sugar added to it. Plain flour- No need to sift this flour. It all just gets mixed in. Eggs- Room temperature to make sure that they incorporate into the muffin batter. Butter- You can also use margarine here too. It needs to be very soft so that it can mix well with the sugar and banana."