In a small food processor, pulse together the goat cheese and the crème fraiche until smooth. Season with salt and white pepper as desired. Cover with cling film and keep in the fridge until ready to use. This will store in the fridge for up to two days.
When ready to assemble, I recommend using a disposable piping bag with a star nozzle. This is an easy and pretty way to get the mousse into the small cornets and also looks nice if you chose to serve the mousse on a crostini. Pipe the mousse into or onto the cornet/profiterole/crostini. Top with garnish of your choice, if desired.
It is best to serve within 30 minutes of making as the cornet/profiterole/crostini will start to soften from the moisture of the mousse. To present them, I like to stand the cornets up in a bowl of red lentils. The colors work great and the lentils hold the cornets upright.