Place the sweetener and butter in a small saucepan over medium low heat. Whisk or use a wooden spoon to continue to stir for about 3 minutes or until golden in color. If butter separates, take off heat and whisk vigorously.
On low heat, add heavy cream slowly and continue to stir for about 3-5 minutes or until the mixture thickens and coats the back of the spoon. Should be runny but not solid. Remove from heat.
Fill egg molds just about 1/4 of the way up with caramel and freeze for 30 minutes while you prepare peanut butter layer.
Prepare Peanut Butter Layer
Add peanut butter and butter to a microwavable bowl or heatproof bowl and melt together for 30 seconds - 1 minute. Stir until smooth. Add sweetener and taste.
Remove egg mold from freezer and add a spoonful of peanut butter mixture over the frozen caramel. Set it back in the freezer for 30 minutes.
Assemble
Remove 6 of the frozen peanut butter caramel from egg molds and set aside on a parchment paper lined baking sheet pan. Place the other 6 back in freezer while you work with 6.
Make chocolate coating by melting the chocolate chips and butter for 30 seconds in the microwave. Or use the double boiler method.
Stir until smooth.
Pour melted chocolate mixture into the 6 empty molds to coat sides of mold, half way up the molds.
Drop the frozen peanut butter caramel into the chocolate and press down so the chocolate encases the peanut butter caramel.
Spread more chocolate with a spoon to completely cover egg. Repeat with remaining 6 frozen peanut butter caramel. Refrigerate to set about 30 minutes to set.
Store in an airtight container in the refrigerator for up to 7 days or freeze for up to 3 months.
Keep refrigerated until ready to serve. Let them sit out to come to room temperature for just a few minutes.