Reply What hapened with my cupcakes?

Sweet Heaven Cake Design ...

thanks for your reply and advice. The cupcakes were for 20 minutes in my oven at a temperature of 325 ° F. I inserted a toothpick in several of them and this came completely clean them out so the oven. a minute or two, began to sink and reduce its size. Really were cooked and delicious … but let me calm as narrowed
I used the recipe for White Velvet Wedding Cake I thought maybe it was just filled cupcakes but were about 2/3 as I always do …. My oven is electric and all my cakes and cupcakes the cook to 325 but the first time I cut and sink as well.