Yes, you can make fresh cream frosting and prepare the mousse. Since I had leftover frosting I used it. You can use leftover frosting straight from the fridge. Make sure the leftover frosting is not spoiled
if you prefer rose milk cream | or rose cream you can skip pudding mix. for a smooth rose milk mousse texture, I would recommend pudding mix. Without that rose milk cream tastes yum but the texture might slightly vary.
You can use white chocolate pudding mix or any pudding flavor that goes well with rose flavor. If you don't have pudding mix, use little cornflour.
rose mousse or rose milk cream depends on the heavy cream frosting texture