What is the best way to: To make two ingredient Nutella Mousse

Select from:
[a]. Gather ingredients (Nutella spread and whipping cream), gently heat Nutella, then beat whipping cream until it holds it shape, gently combine the two, chill, then serve.
[b]. Gather ingredients (Nutella spread and whipping cream), gently heat Nutella, then heat whipping cream until it holds it shape, gently combine the two, chill, then serve.
Answer:
[a].