Were they baked all the way through? Did you test one to make sure? The tops are awfully white; I have never seen cupcakes that white come out of the oven. Many times you may think your cuppies are done because they have been in the oven for the length of time the recipe calls for, but depending on differences in altitude and humidity, they may need more or less time than listed. Always test one of the centre cupcakes to make sure.
Another thought … What temperature was your oven at? And was it on convection? I bake my cakes and cupcakes no higher than 325 F, and never on convection.
