I've made these a few times. I like them because they're easy to make and very versatile. The first time I stuck to the original recipe, (minus the topping). They were nice, but it gave me the idea to try other fillings. I've made Nutella centred muffins and I've just made chocolate muffins with white chocolate spread in the centre and vanilla muffins with jaffa cake chocolate spread in the centre.
I prefer this style to the traditional chocolate chip version.
I have a horrible ferocious fan oven and have learnt that 20 minutes on 160 oc works best with my oven. Judge your own oven to get the best results ☺ - 19 May 2016