Step 1: In a large bowl, combine the powdered sugar and peanut butter and beat until smooth.
Form firm peaks by whipping the heavy cream and vanilla extract in a separate dish. Whip gently, but not too vigorously.
Combine the peanut butter and whipped cream by gently folding them together. For a lighter filling, it's best to keep some air in the whipped cream.
Divide the filling among the little graham cracker crusts and spoon it on top. To make the tops smooth, use a spatula.
To make sure the filling sets, chill the pies in the fridge for at least two hours.
If you'd like, you can top it up with some little peanut butter cups or chocolate shavings when it's time to serve.