For the pudding, whisk together all ingredients in a bowl. Cover and transfer to the fridge to sit overnight and turn into pudding (give it a stir every so often if you think of it).
For the sauce, mix together all ingredients in a bowl. Cover and refrigerate until serving.
To serve, layer the pudding and sauce in individual glasses. Top with pecans or walnuts if desired.
Store leftovers covered in the fridge for up to 5 days.
Notes
Vegan-Friendly: Use canned full-fat coconut milk instead of heavy cream.