Blend nut butter mousse ingredients until smooth. Pour into a saucepan over medium heat.
Bring mixture to a gentle boil, stirring occasionally for 8-10 minutes to avoid burning or sticking at the bottom. Taste mixture and adjust sweetness if needed. Remove from heat. Let it cool to room temperature. The mixture will thicken as it cools.
Assemble parfaits by adding berries to a small serving dish, drizzle on nut butter mousse, repeat for added layers. Top with cacao nibs if desired.