Need help - cannot make light fluffy brioche doughnuts!

So the picture I’ve attached is for the kind of brioche donut I want to end up making however all I’m ending up with is bread-like dense doughnuts which don’t have the same crumb structure and texture as the one in the picture...please help me I’ve tried so many recipes none of them have gotten me close! 

The last one I tried was this one 

https://www.chefsteps.com/activities/how-to-make-bulletproof-fluffy-yeasted-doughnuts-at-home

But it was a huge disappointment! 

Does anyone have any recipes or tips? Would greatly appedciate