You may need to adjust these amounts, but this is a guidleline based on what works for me.

Ingredients:

fluid whipping cream (1 cup)
pure cocoa (3-4 tablespoons)
Splenda (2 packets)
vanilla to taste (optional)
nut butters (optional)

Pour 35% cream into a small bowl. Stir in Splenda packets until dissolved. Add vanilla to mixture. Add one tablespoon of pure cocoa until blended. Continue to add cocoa powder until a mousse-like consistency is reached. This requires a lot of cocoa, but eventually it will thicken. Do NOT beat or whip the cream. You merely have to keep adding the cocoa and stirring gently until all is thick and well blended.

Once it is done, you may add some swirls of nut butter, depending on your plan. I prefer almond or peanut (ok technically legumes, but good Reeses subsitute!).

Carb estimate: 5 carbs/cup