Make this part a few minutes ahead of time, so it can cool just a little:
1 cup Reece's Peanut Butter Chips
2/3 cup heavy whipping cream
Microwave the above just until the cream gets steamy hot, but not boiling. In my microwave this takes about a minute. Remove from the microwave and whisk until the melted mixture is smooth.
1/4 cup brown sugar
1 teaspoon vanilla extract
Whisk until smooth and set aside to cool a little.
With electric mixer, start whipping 1 1/2 cups heavy whipping cream.
When it gets about "half way" to being whipped cream, slowly drizzle in the peanut butter chip mixture.
Continue whipping until it gets to the consistency you like.