🌻First start Chocolate mousse (so it can cool):
In a small saucepan, whisk: 5 Tbsp sugar, 5 Tbsp cocoa powder, and 1 packet gelatin. Whisk in 1 cup cold water and 5 Tbsp milk. Place over medium heat and bring to a boil while mixing constantly so the chocolate doesn't lump up. Remove form heat and let cool to room temp (about 1 & 1/2 hrs).

🌻Second Make Vanilla Mousse:
In a small sauce pan, combine 1 cup milk, 1 tsp vanilla, 2 packets gelatin and whisk together. Place over medium heat and continue whisking until steamy (DO NOT BOIL) then remove from heat and cool until just warm. OR you can Transfer to a different dish to cool faster.

Once milk is no longer hot, In a large mixing bowl, using an electric mixer, beat 1 cup heavy cream until fluffy and spreadable (1 1/2 to 2 min on high speed). In a second mixing bowl, whisk together 1 cup sugar and 2 cups sour cream until well blended. Fold in whipped cream then while using the mixer on low speed, slowly add warm milk mixture, scraping down the bowl as needed and mix another 30 seconds to ensure it's well blended.