I have seen these different flavored candy crunches in cake decorating shop and wanted to know if there is a recipe to make them. you know a homemade version of it.

Do you mean to make the crunch itself ??
I know you can make a rice krispies bark. And get a crunch like that. I use the store bought crunches they are wonderful and there are lots of different flavors.

I have seen the boysenberry crunch and was wondering how it is made...

I have seen it sold but have no idea how to make it.

It seems very similar to rock candy to me; maybe you could try a small batch and see what you think?

My thought is about the same as Callyssas. Just boil some sugar syrup, add your flavor (jam??) boil a bit more and let harden, then crush it up.