Super Moist Banana Muffin

My son came over for dinner and I thought that I should make some snacks for him to bring back.  Furthermore, those bananas hanging there were ready to be mashed.  I've tried many banana muffins and mostly are very dry and does not have the natural banana flavouring.  So, if you have "very ripe" ones and does not like to eat it as a fruit, use them to try out on my receipe.

Ingredients:
210g self raising flour
200g unsalted butter (room temperature)
200g sugar
4 eggs
2-4 ripe bananas (350-370g)
1.5tsp vanilla extract

Method:
1. Beat eggs till foamy, set aside
2. Cream butter and sugar
3. Fold in eggs and flour
4. Mix in mashed bananas
5. Bake for about 30mins at 180C until the top of the muffin is golden brown and when tested with an inserted skewer, it comes out dry.

Here are my standard baking basics:
Flour - sieve flour to get rid lumps
Butter - usually use unsalted
Sugar - best use castor
Eggs - usually large @65g each

Tips:
1. To beat eggs foamy, best use a beater for about 10mins (add abit of sugar + vanilla extract)
2. When seeing curd during the folding of egg and flour, alternate batter or add flour.
3. Do not overmix and bake immediately.