These are both good ideas. If using a mold, make sure that you use wax or parchment paper underneath (or slightly grease the bottom/pan).
Just use melted white chocolate. Don't add any cream to it to make a ganache. It won't be hard enough as white chocolate acts differently to regular chocolate. If you are piping onto parchment paper, draw correct sized circles on the bottom of the paper and pipe the border first and fill in.
Living gluten/dairy/sugar/caffeine-free and loving it!