Do ahead: Prep the strawberry and banana per instructions above. Spread out on a baking sheet and freeze overnight.
In the morning, add the frozen strawberry and banana to a blender with the cacao nibs, oatmeal, and milk. Blend until smooth.
Whisk the cream in a bowl until stiff peaks form using a electric mixer or by hand using a whisk.
To serve: Transfer the smoothie to a glass. Garnish with whipped cream, and diced strawberry. Use a vegetable peeler for the dark chocolate bar to make chocolate shavings over top.