Hi, what is the recipe/ingredients for this purple drizzle? and what glitter is used & how is it added? Thanks (not my pic)

That looks like gelatin glaze with disco dust (which is really not intended to be ingested).

oh ok, thank you. What about a purple ganache,  does anyone have a recipe for that?

I made that cake last week using purple ganache. The ratio for most white chocolate ganache is 3:1 . Little bit of corn sirup is suppose to add some shine to the ganache. (Not sure if it realy add anything though...)

Here is the recipe

1 1/2 cup white chocolate

1/2 cup heavy whipping cream

1tbsp clear corn sirup

(I had more than enough ganache for my 8inches cake. 1cup chocolate and 1/3 cup of cream would have been ok)

For the color, I've use violet wilton candy color. 

https://www.cakecentral.com/gallery/i/3416186/emoji-cake

Wilton makes Candy Melts with glitter in them, but I don't know if they have purple.