In a large bowl mix the butter by hand with 1and 1/2 cups of the Splenda pulsed in the food processor until looks like powdered sugar and cocoa powder. Stir in the vanilla.
Add the peanut butter and mix until the texture resembles small beads. Add the milk slowly, beating with a mixer until very creamy. Add the remaining 2 (and up to 3)additional tablespoons of Splenda pulsed in food processor if necessary to achieve the desired consistency.
