01 - Place the vanilla ice cream, whole milk, peanut butter, and vanilla extract in a blender.
02 - Blend on high speed until completely smooth and creamy, approximately 30–45 seconds. Pause to scrape down the sides of the blender if necessary.
03 - Taste the mixture and modify thickness as desired: add more milk for a thinner shake or additional ice cream for a thicker consistency.
04 - Pour the finished shake into chilled glasses to maintain optimal temperature and texture.
05 - Top with whipped cream, crushed peanuts, and chocolate syrup if using. Serve immediately with a straw and long spoon.