In a blender, combine ice cream, milk, peanut butter, and optional vanilla extract, and blend until well-combined and pourable.
Pour into glass(es). Top with whipped cream and additional toppings if desired and enjoy.
Notes
*Use ½ cup milk for a thicker shake, up to ¾ cup for a thinner one.This recipe makes about a 12 to 16-ounce (1½ to 2-cup) milkshake, enough for one restaurant-size serving or two smaller ones. Approximate nutritional information is for 2 servings without optional toppings.