In a medium saucepan, melt peanut butter over medium heat.
Add milk to the melted peanut butter. Heat milk and peanut butter to just under a simmer, whisking until the mixture is well-blended. Remove from heat.
Whisk the heavy cream into the peanut butter and milk mixture. Then whisk in the sugar until sugar is dissolved. Then stir in the vanilla extract.
Transfer mixture to a medium-size bowl and allow to cool at room temperature.
Cover the bowl with plastic wrap, making sure the plastic is touching the top of the mixture to prevent a skin from forming. Place the bowl in the fridge overnight or at least 3 hours.
Churn according to your ice cream maker's instructions and serve immediately for soft ice cream or freeze for 3 hours or more until the ice cream is your desired consistency.