MVC “Content Block” Widget?
In Classic MVC mode, you are on your own. In Pure MVC mode, you can use any MVC widgets that "you have developed". If you would like to use the built in widgets, such as a content block, you will need to select either the Hybrid MVC mode or the classic Web Forms mode.
However, you could develop your own MVC widget version of the Content Block. Follow this video tutorial on how to create an MVC news widget, but substitute the content APIs instead.