ok, i do this in proportions not in measurements, so you'll have to play with it yourself and get the texture you want:

Frosting (cause it's good or for parillo cup cakes etc.)
3 pts: Natural Peanut Butter (creamy)
1+/- pt: Cocoa Powder
To Taste: Stevia (Splenda, Sweet n Low, etc.)

More Solid Choc:
2 pts: Natural PB (creamy)
1+ pts: Cocoa Powder
to taste: Stevia (Splenda, Sweet n Low, etc.)
If Desired: Almond flour (will help solidify and adds texture/flavor)

I put the cocoa powder in the bowl then the peanut butter, start mixing, add a little sweetener, stir more, add some more sweetener, stir more, add the rest of the sweetener and mix until it's all one really REALLY dark color. There shouldn't be any chunks or visible spots of peanut butter.

Cals depend on how much you make and what proportions you use... enjoy!