Add cream cheese, peanut butter, icing sugar & vanilla extract to the bowl of a stand mixer (or use a hand mixer) and beat until smooth and creamy and there are no lumps.
If the mixture is firm enough to roll, you can roll it into balls right away, otherwise cover and chill in the fridge for about 1 hour until it has firmed up. Roll into balls (about 1 tablespoon big) and place on a tray lined with baking paper.
Refrigerate for about an hour until firm.
Using a double boiler or in the microwave melt the chocolate. Roll each truffle in the chocolate until fully coated, remove using a spoon and place back on the tray and refrigerate until chocolate is set.