Er... when does the creme fraiche go into the rhubarb crumble??

Hello... there's a recipe on here for rhubarb crumble... but it doesn't say when to put the creme fraiche into the mix...?
Can anyone enlighten me? Thanks.

Creme fraiche into rhubarb crumble

I would imagine you would serve the creme fraiche with the crumble rather than
incorporate it in the recipe but I may be wrong!