In a large bowl, beat together the cream cheese, peanut butter, sweetener, vanilla extract, and heavy cream until well combined and smooth.
Spoon into 12 to 15 popsicle molds (depending on size) and tap molds firmly on counter to release as many air bubbles as you can. Place popsicle sticks in the center of each (wooden sticks are preferable as they stay in the popsicles better).
Freeze 4 hours until firm. Remove from molds by running under hot water or placing in a bow of hot water for 30 seconds, then gently twisting the sticks until they release. Keep in freezer until ready to dip in chocolate.
Line a baking sheet with parchment or waxed paper and place in freezer. Set a metal or ceramic bowl over a saucepan of barely simmering water (do not allow bottom of bowl to touch water). Add chopped chocolate and cocoa butter and stir until melted. Remove from heat.
Dip a popsicle into chocolate about half way, then let excess drip off back into bowl (you can hold upright and twist to get some interesting chocolate drips down the sides of the popsicle).
When chocolate is firm, place finished popsicle on cookie sheet in freezer and repeat with remaining popsicles.